AN ~ie~ >~ t AX ~5 ~44r L+'A . -AO, I t , ISA In this issue W i n t e r 1 9 9 7 V o 1 I Il Ct 4 4 N ut m h c r A2? \tAReiui't Rio t ReF R i-s-sttii Pt isii t o III A-e\ t it \tk V iIitiz \uI, E~xiitiz i m i uIHIN. At BI R\ [ \1\ S~ JAME S I . MARION............Director JAMES R. ROBERSON...........Editor CATHE-RINE L. SMIT[H .. Associate Editor ILEIGHI A. STRIBLIING .. Associate Editor TERESA F. RODRIGUEZ ... Art Designer EIT~ttORItAL COMMITTI: I Art i (happetkau. Assouciate Protessor of Foircstsy: Robert Nclson. As~sociate Pirofessot of Ag*i cultutral Economuics and Rural Sociologsy- Airt As ery, Protesso. School of Human Sciences: Das id SitrinfelloA. Associate Professor of Animal Health Research: Beth (luerial. Assistant Prof essor of' Agronomy and Soils: Geoffrey /ehntde .. A ssocti ate Pirofessot ouf I iitomol ogy: atnid Ros Ro het son. tditor " Noic. Mlention of ti ade niamies dloes noi intdicate enidoirscmtent hs the \labana Ai iculitural Expet imeini Station oi Auburn U nix cisity of one brand ox er another. Anv x se oft pestucide raties in excess oft labeled amounts in research reported does noti constitute irecoimmendaioi oi such rate. Such itse is suiply part of the scieniic invesi- Cdin Of ieeeSSair to iii alutii 5aiouils materi als No chemxical s1houlId be u sedl at rates ahov e those permititted Its the label. tntootation cota~ined herini is av ailahle ill all peirsons wxithout tegard to race. colotri sci. oxi natioinal 0112111. A labama A, r)itflttfral Et~perioieut .Stooi High'/lii/tts oI Agiculo/n ul Reseirch t Vol. 44, No. 4, WVjite 1997 Toxic Fescue Smears Forage-Fed Beef 3 Soil Ni trogen Testin e Can Help Adjust N Applications for Alabama Corn 5 June Rainfall Critical for Optimum Cotton Yield 7 \ "Bud -boring"' CutwAor m: An 1 nu~suial Pest of Nativ e Rhododendrons 8 Recycled Waste Paper Pellets Provide Weed Control in Container Production 1I 1, Planting Cotton Before May Risky Business in \orth Alabama? 14 ,NcA Cheimical May Prosvide A nswer to Control of Bacterial Spot of Peach 18 Respiration Patterns Play Key Role in Pest Biology 20 \\ etlands Impros e Effluent Qu~ality from a Channel Catfish Intensiv e Culture System 22 ON THE COVER: AAES reseaicher loads feed into planter for cottoilnt ilan date tudy. See related story on page 14. Happy Holidays to everyone reading this message. The holiday Season allows us to look forward to the coming New Year, and also review the events of a year gone by. As the history ot Auburn Univ ersity agriculture is written. 1997 wsill he remembered as a time ot change and perhaps turmoil beN onl most "normat" yeats. Out of this change, wc trust that a stronei Alabama Agricuiltuiral Expeiriment Station (AAES) 'Aill emerge as w~e focus our efforts on more cooperative research, bet- ter inv ols ement ot our clientele in AAES programs, and increased extramural Support tor programs. The future of AAES will be shaped in part by a Search Committee for a new~ AAES Directoi (and Dean of the CollIege of Agriclturie) to take my position by Oct. I. 1998. Also, a new Dean of the School of Forestry soon wAill be named to replace Dri. Emmett Thompson. wAho retires in early 1998. Emmett, 'Ac congratulate you and thank you foi your years of setvice. Your leader ship wAill be missed by AAES. We also congr11atulate Dr. Tim Boosineer. who is completing his first year as Dean of the College of Veterinary Medicine, wAhere the AAES Supports animal health research. An AAES Faculty /Industry Council composed ot agribusiness and AAES faculty repiresentativ es wAill meet in mid- December to turther guide our research directions. This Council wAill be actis e loi a number of yeairs, and y oui input and ideas are wAelcomei by its iieiibers. A list of members may be obtained by calling our oftice at (334) 884-2237. An agricultural bond issue fr om the agricultuire, forestry, and sveteinary medicine sectors of Alabama also will influence the future of the AAES. If passed by the legislature and general refer- endum in 1998, this bond issue wsill prosvide newA and reinosated buildings for- AAES-related pograms oni the Auburn and Alabama A&M University campuses. Finally, the history of the AAES is truly being 'Ariitten and recorded by the best. Ms. Leigh Stribling, new Associate Editor in the Office of Research Info~rmation, 'Aill be chroniclin. 1997 f0i the AAES through oui annual ieport. We welcome hei to AAES. And Dr. Joe Yeager and Mi. Gene Stevenson are spearheading an effori to bette* document the full history of Auburn agriculture. Again, Happy Holidays from all of us at AAES. 1It0 ioxC LESCUE 5MAEARS FORAGE-FED BEEF Amv Shnonne, David Brai nsin, an/d Naiu \ Gren OXIC FESCUE could be largely responsible for the poor image of forage- fed beef in the United States. This is the conclusion drawn from a recent AAES study which indicated that a consumer taste panel could distinguish clearly between beef from cattle that were grazing toxic fescue, compared to beef from animals grazing other forages, or finished on a concentrate diet in the feedlot. -5 iN- i A ~i": Calirris/ld on iN prvide b/ck/ o/ simhilacii /ii to those Niuil hed in a fe Cd/ot. Tall fescue (Festuca urtndi- nacea) is the most widely grown improved pasture species in the United States. It occupies about 35 million acres, and supports approxi- mately 10 million brood cows. However, 950 or more of these pas- tures are infected with an endophytic fungus. NeotvIphodiurm coenophialiin. Fescue that is infected with this fun- gus is more tolerant of stress, but it is somewhat toxic to animals and causes reduced weight gain and reproductive levels in beef animals, especially in late spring and summer. Other signs of toxicity include elevated body temperatures, long hair coats, excess salivation, reduced time spent grazing, and more time spent in shade and water. Despite these animal disorders, cattle produc- ers are reluctant to replace infected fescue pastures with alternate forages because it is costly to do this, profit margins are mostly low, and no other forage species is as hardy and widely adapted. Consequently, infected fescue will remain a very important forage in beef production for the foreseeable future. Although forages form the base of cow-calf production in the United States, beef animals typically spend three to ii \inlhN ii a Fccdlot Toxic Fescue, continued on page 4 A labaIa Agricultural Lxperimentil Statioi Highlights ol'Agricultural Research Vol. 44. No. 4, Wiuter 1997 loxic Fescue, continued tiom pae 3 II1 (ail 11 i uncu iiL dick> I) ()l iO process ing and distribution into the retail market. The feedlot phase of pro- duction is usually the most expensive. Furthermore, this phase is strongly influenced by the price of corn, which tends to fluctuate widely xith corn yield. thus affecting price of cattle and the risk associated with cattle produc tion. ex en at the cow-call lexel. Unfortunately. feedlots also cause seri- ous enxironmental hazards and are in question regarding animal welfare in many cases. As an alternatixe to beef from animals Iinished in a fcedlot. borace- lcd beel has been considcred and ex al- Lated in many studies. This production option is used widely in other coun- tries because of the relatiely high cost of grain in most other parts ot the world. Howevei. in almost exery study conducted in the United States, taste panels have been able to distinguish between beef from animals finished in a feedlot and forage-fcd beef. Specifically. beef from animals fin- ished in feedlots has been almost exelusixely preferred. Careful examination of proce- dures used in these studies suggested that this distinction was partly due to the fact that cattle on feedlot diets were I~r I \ c n ,Ii i-; ;ns o e'rr usially heaier than thosc Irom J'orace diets. Therefore, an AAES stidy was conducted to examine this by tak- inc both leedlot and forae-fed ani- ials to a similar level ol finish prior to processing see High/ligi of. Agicultural Re me(rchI1. Vol 42(4) Winter 19951. In this case cattle on the toiae fed diet had gi azed Maishall annual ryegrass (Iolium nndtub, uni). and a consumer taste panel could not distinguish clearly betwcen steaks obtained Iiom feedlot cattle and those obtained Irom animals finished on pas- ture. Since results fi-om this study differed fi-om those of most othei stud- ics that compared feedlot and forage- fed beef, additional research was con- ducted to investigate possible explana- tions. One obxious difference between this study and otheis was the difference in the forage species. Because tall fes- cue is so widely growxn in the United States, a second experiment was initiat ed to mx estiate the possible effe~cts of infected fescue on borae-fed heel. In this experiment Angus or Ancis x Heieford steers crazed infect- ed or fungus-free Kentucky 31 fescue, or xere fed a hich-concentrate diet in the feecllot. Fixe animals were assicned to each treatment, and fin- ished weichts were 1.016. 1.046. and 1.058S pounds rri.'5Lcti\ clx Ribev e Consumer Response to Ribeye Steaks from Various Finishing Diets Treatments Aroma Juiciness Feedlot 6.80 7.35 Ryegrass 6.97 6.65 Ryegrass+hay 6.29 6.35 Fungus-free fescue 6.94 6.61 Fungus-infested fescue 6.63 5.35 The maximum full scale of score was 14 cm. Tenderness Taste Over all prefer ence 7.88 8.44 8.33 7.12 7.58 7.75 6.69 7.61 7.38 6.51 6.97 7.07 5.30 5.81 5.58 steaks from these animals were evalu- ated by a xolunteer consumer panel of 8(0 people ranginc in ace from IX to 6(0 years. Panel members were regular meat consumers, and most had partici- pated in the prex ous study. Meat samples were oven- broiled to an internal temperattre of 158oF, as ii the first study. Panl mei bers were asked to rate flaxvor/aroma. jiuiciless, tenderness. taste, and oxerall preference of the steaks on an instrlc- tured linc scale. Data from both expcri- ments were combined in a pooled analysis. Steak from cattle that had crazed infected lescue xas rated infe- rior in all attribites except aroma. With regard to juiciness. tenderness. taste, and oxerall preerence it was rated distinctly loer than beef from animals out ol the teedlot or from diets containing ryegiass (see table). In rela- tion to juiciness and tenderness it was distinctly inIerioi to beef trom animals that had grazed Iungus-free fescue. but this difference was not clear in relation to taste and oxerall preference. Resilts from this stud> shoxx that infected fescue could be largely iesponsible for the poor image of for- aue-fed beef obtained in other similar experiments. [Fiirther research is need ed to determine ho long it takes alter cattle are moxed from infected fescue to an alternate diet belfore the negative eIfects on the meat are eliminated. Bonne s a Post Doctoral Felow of utrtion and Food Science: Bransby is a rofessor of Agronomy and Soils and Gr een is a former Professor of Nutrition and Food Sc ence AlabamaSii~i . t,'ricihurl// o p /)ri tc .Suuuoui H-igi.'llightms oftA uricultua R~esearch Uol. 44, No. 4, Wint', 1997 (Iou/ e C('. Aitc hc // ITROGEN APPLICATIONS for Alabama corn ix hit or miss. Current standard recommendations are based on long-term research throughout the state, but general recommendations Fail to take into account variations due to weather, rainfall, manure applica- tions, residual soil nitrogen and situations where all the nitrogen may be applied prior to planting. To compensate for these uncertainties. growers may apply more nitrogen than is needed by the crop, resulting in increased production costs and potential for nitrates leaching into ground- water or running off in surface wate. AlabaIna Agricultural E perimient Station Higlights / Agricultural Research Vol. 44. No. 4. Winier /9'7 Several techniquex have been used in Alabama and in other parts of the United States to line-tune nitrogen applications. Multiple or split nitrogen applications help. Fertication is useful wxhere i roweis irriate. Some ,rowers take xhole piant samples early and monitor the car lea nitrogen at tasseling. The chlorophyll meter has shown promise for identifying nitrogen deticient corn at side dressing time and especially at ,il king. All of these are uselul tools. but each has its own limitations. Most tend to encouiage overiapplication ol nitrogen fer- tiliLers. Soil nitrogen testing has not proved very uxeful in the humid eastern U.S. hecauxe most nitrogen fertilizers are mobile in the soil. lhe, don't stax around long lol loxing heavy rainfall. However, organic- hased nitrogen fertilizers such ax manures. wxill leaxe some residual organic nitrogen in lie soil. The presidedress soiI nitrate test PSNT) has pirox ed helpful in the northeast- ein and midx estern U.S.. especially where animal manurex haxe been applied to the soil. It has not been extensively evaluated in the deep South. The PSNT involves taking a soil sample just prior to side dressing the corn crop xith nitrogen. The soil is tested for nitrate-N either by a laboratory xith a very quick turn-around time or xwith portable equipment. TI he decision to xidedresx the crop is made based upon the concentiration of nitrate-N in the soil. It has worked in Ohio. Pennsylxania, Vermont. Tennessee, and other xtates when the primary nitrogen xource hax been animal manures. An AAEFS project in cooperation with the labamia (ooperative Soil Nitrogen, continued on page 6 120 100 3 . 80 S.. 60 >0 Critical soil nitrate-N = 30mgkg v 40 '7 20 0 5 10 15 20 25 30 35 40 45 50 55 60 65 Plow layer nitrate-N, mg/kg l71i 1'.\\l "! tn c,//' C( lire at /nriic iiiii l , /hic /I(, (/ / ir mlcdrcs\ .A appiiiliatioi\ ill iihcw or/1--ill-111 sII)s ini Noth AIlabiLaL. Nun- irrI,igted vie /ds range'cd /iomi 50) to 2 1/bIshels pr ci ieIL onI (lhese on-I arm) i(e/t/ in /992-1994. ri/f onI ales/i)I takenI /1ust /)/ioL to) si(Ie/c - Ig, corLnLit li iognL. Plots ii tie bulak IrAi/l receriveI /bro iler litter at /7/U/t ii g. IIUL IL' ii the, /oiregiro/l reeiedl no1 N at Soil Nitrogen, continued from page 5 Extension System and supported by the Alabama Wheat and Feed Grain checkoff program has evaluated the PSNT and the chlorophyll meter in 20 on-farm tests in North Alabama and in a field experiment at E.V. Smith Research Center in Central Alabama. All sites involved manure appli cations, mainly poultry broiler litter. because manured fields are most likely to have significant carryover of residual nitrogen. In Noith Alabama. the PSNI predicted the need for sidedress N on most of the 20 growers' fields where it was evaluated in 1992 through 1994. A critical value for applying sid- edress nitrogen to corn at the V6 irowth stage (six leaves) is about 30 parts per million (ppm) of nitrate-N (see figure). This is a little hieher than that used by other states (2 to 25 ppm). The PSNT in North Alabama also showed that much of' the iitiogei in bioile litter was lost if it was applied more than one month prior to planting corn. In these cases, additional. sidedress fertilizer nitrogen was needed for the crop. Manure applications moie than one month ahead of planting coin is not a recommended practice! All broiler litter on the experi- 6 ment at E.V. Smith Research Center was applied just ahead ot planting and incor- porated using a field cultivator. Residual broiler litter was that which was applied the previous spring: no additional fertiliz- er was applied to the curent crop under residual broiler litter. Although the PSNT seemed to do a reasonable job of predicting the need for sidedress nitrogen in North Alabama. data from 1995 through 1997 on a fine sandy loam of the Coastal Plain at E.V. Smith Research Center in Shorter indicate that the PSNT is not a reliable measure- ment of residual soil N on these soils. Sandy soils, a warmer climate, and slight- ly higher rainfall contribute to greater nitrogen losses in Central and South Alabama. The PSNT found no N carrix- over in the soil from broiler litter applied the previous year although corn grain yields (see table) and leaf nitrogen analy- sis indicate that some residual effect was present. The PSNT can detect some N carryover from high rates applied at planting. but the anount detected is very small compared to concentrations report- ed from the Northeast. Midwest. and North Alabama. Although chlorophyll meter readings from corn at the V6 and at early silking stage are not piesented in this report, these tests continue to show that the chlorophyll metei has piromise foi detecting late-season N deficiencies. Mitchel is a Professor of Agronomy and Soils Corn Grain Yield and PSNT Soil Nitrate Concentrations at E.V. Smith Research Center, 1995-1997 Treatment 1995 Corn PSNT PSNT grain No 3 -N NO-N yield 0.8 in. 8-f in Corn grain yield 1996 PSNT N0 3 -N 0-8 in PSNT NO N 8- Iin 1997 Corn grain yield bu.lacre ppm ppm bu.Iocre ppm ppm bulacre 24 6 4 57 5 4 64No N Am. nit. at 60 lb. N/a 43 6 5 140 5 4 112 Am. nit. at 120 50 9 9 140 8 1 130 Am. nit. at 180 47 1I 8 126 8 7 126 Am. nit. at 240 53 23 13 110 10 13 132 B.L at 120 43 6 4 108 1I 4 118 B.L.at 180 55 7 6 108 6 5 112 B.Lat 240 59 10 1I 134 7 7 135 Residual B.L. at 120 30 5 4 75 4 4 69 Residual B.L. at 180 39 6 5 103 4 4 76 Residual B.L.at 240 54 5 5 121 4 4 83 Am. nit. = ammonium nitrate; B.L. = broiler litter rates are in pounds N per atre per year; residual B.L. are rates applied in previous years. All ammonium nitrate N was applied in equal, split applitations. Broiler litter contains an average of 60 lb. N, 60 lb. P,0 5 , and 40 lb. K 2 0 per ton, therefore, the rates used correspond to approximately two, three, and four tons per acre, respectively. Highlights of Agricultural Reserch Vol. 44, No. 4, Winter' 1997 JUNE RAINFALL CRITICAL FOR OPTIMUM COTTON YIELD Scott Jack.son,. Charles Mitchell, and Ellen Bauske MANY STUDIES have been done on the effects of annual precipitation on cotton yields. Few have investigat- ed the correlation between monthly rainfall and yields. Recent AAES research indicates irrigation in late spring or early summer may be criti- cal to cotton production. All parts of Alabama receive an average of more than 50 inches of rainfall annually, makinc this one of the highest rainfall areas in the coun- try. However, rainfall distribution during the growing season often results in short-term droughts or excessively wet periods in many parts of the state. Due to the absence of large frontal weather systems during the summer months, most rainfall in Alabama during this period is attrib- uted to isolated thundershowers. Identifying critical periods when rainfall may have a particularly significant effect on cotton yield could help producers with future decisions regarding planting, irrigation, field operations, etc. Although only 5c/ of Alabama's cotton land is irrigated, interest in irrigation is growing. Annual yields from standard fertilized treatments on lone-term cot- ton fertility experiments were studied at four locations in Alabama's Coastal Plain: Auburn (1978-1994), Brewton Experiment Field in Brewton (1992- 1996). Wiregrass Substation in Headland (1992-1996), and Prattville Experiment Field in Prattville (1992- 1996). Long-term yield and weather records on file at Auburn University. and data from the Alabama Weather Information Service (AWLS), were ?l in the study. Statistical correlations re run to determine any trends or sig- iticant relationships between monthly riintall and annual cotton yields. June rainfall was significantly correlated with cotton yields at all loca- tions (see figure). Rainfall totals for other months of the growing season showed less significant correlation with cotton yield. Cotton yields at Prattville showed highly significant dependency on both June and July rainfall. In June in most of Central and South Alabama, cotton is squaring. Dry weather during this critical period will slow down veg- etative growth. Reducing early growth would mean a lower and later potential yield, due to the stunted size of the cot- ton plant. The plant would resume veg- etative growth during better weather, but probably set the resulting squares at a less favorable time of the season. June is normally a dry month and has t high c\apotranN'pirat n rate. June Rainfall, continued on page 8 Alabama Agricultural E perimtent Station Highlights of iAgricultural Researh Vol. 44, No. 4, Winter 1997 June Rainfall, continued from page 7 c\ tl itpo4ispiratioi lrauc can aggravate droug11ht conditions. The month of May is normally drier than June. which would tend to set up a moisture deficit in the soil as June begins. Plentiful rainfall during this period, which would help off set the detrimental effects of high evapotranspiration rates as well as any soil moisture deficit, appears to be critical in establishing a healthy plant with high yield potential. A possible explanation for the high correlation at the Prattville location may be the soil. The Prattville soil has a higher clay con- tent than any of the other study sites. Even though clayey soils tend to have a higher water holding capaci- ty. under extreme drought condi- tions the matrix or structure of the clay may hold water so tightly that the plant cannot extract and utilize the existing moisture in the soil. Thus a soil with a high clay content with more actual water in the soil than a sandy soil may have less actual ux I:il \\ ater for the nl:ml1 A similar phenomenon has been observed by researchers on North Carolina's Coastal Plain. A lack of high correlation in July and August may be due to excess rain- fall in these months, in some years. which may actually reduce yields. A good example of this is Hurricane Danny in Baldwin County in July 1997, where high rainfall totals were accompanied by destructive winds. In some years excessive rainfall in July and August may lead to excessive vegetative growth and boll rot. Each farm is different and an analysis of local conditions xould be needed, but from the results of this study it appears that when rainfall is not sufficient during this critical period, which for Alabama usually falls in June, irri- gation may be a viable alternative at some locations. Jackson is a Graduate Research Assistant and Mitche is a Professor of Agronmy and Soils: and Bauske is a former Extension Specialist. A 'iBu] AN UNt RHODOD / ;/ 1 "t1/ June rminfallnd seed co1 A ~i.~ l , Imm ohoirc. 11mi er , o frluoclodc ndrou showiiing l,ical sign of lborer attaock ,om- c blooms ofR. austrinum i Ildlmgflo lowc o cuds101 u111)lP/e Mloans of R. canescens 1i1 louiuo p 1 d floiic 1)ls; eAlnan rlima/ddelnron K. canescens ) in itill bloon. 1,ot oil ho i A labauna Agricultural Experinment Station Highlights of Agricultural Research Vol. 44, No. 4, Winter 1997 3ORING" CUTWORM:* AL PEST OF NATIVE DRON S L. L. Hvclw anid U. W. She ake A/ 2 IVE RHODODENDRONS grow naturally in many areas ofAlabama woodlands and several species bloom in spring . pviding welcome patches of color to a countryside note. yet recovered from winter. The attractiv eness of these shrubs in full bloom has made them favorite candidates for "domestication" and adaptation to urban and suburban landscapes. However, cultivation of ~ these native plants has led to a previously unknown pest. For several years, growers of full and complete bloons: damagcd' nativ e rhododendrons in East-Central buds shrivel and die, or produce Pcricl/mnta Alabama hav e been concerned about incomplete, ragged blooms wxith only WHItna is one of "borer" damage to flower buds. a few flowers. Preliminary studies by Alabama's most common cutworms Damage has been most common on AAES researchers Ila c adl i knowxn to feed on a wxide three spring-blooming species, identified the noctnr- ait f pat.I Rhoadndendm carne aen s. R. aus'- nal pest as the x ar- \labutna. the species is triittint and R. alabamnen.c i N under iegated cutwxorm ntcmol soi culture locally as ornamental s. ( Pc r i il do m u in d with vegetable. U'ndamaged buds normal Ix produce xatn iar 1 HacUe. and field ups. Its habits are a Friable. however. ( f' ed reportedly include a tendency to climb and -1iirbing cutxxorms1. It is t!~ C I Jmbin(I Cttxor that i t teCated cutxvOrmn causes a damnage to rhododendrons. ' y Damage to flower budls SbegIi to appeal' tmost v eals diii incr ~ . the first half of February (as early as ~ t , .Ian. 28 in 1994). Larvae sometimes - . 3 t _" _uteed initially on the bud surface. but r!'y t~ry,3ztA+F ? 1 This species was identified by Paul Estes, Associate Pr ofessor Emeritus of Entomology. Cutworm, continued on page 10 \llu/iii <h llspres the 1995 groxx lne season. reeardlesS (If xxhlethier spur oe seed xxere soxxnr on top (it the rvulchi or under the riiulcli (see tahle t. In coritr ast. recx cled crrimhlc Pellets, continued on page 12 Alabamao Agruiinuraol- Lxprinent Station Higihts of Agricmltralro Rceerchr Vol. 44. No. 4, Witer /99c> 1)ccLl. Smith. CliurlcN 11. Gi/liunt../ uncs 11. L. ht (l dN, am/John l l. Olive IPellets, nriiu Id fromn page 1 I pro\ vidcd poor sptrSl control at botih. . depths and who " spurge were sown on; top of the mulch. there was increased spurge growth com- pared to when the seed were sown under the crumble mulch. With recy- cled crumble thereu was greater spurge pla(11hs t/at are (i/i( number per pot at 30 days after treatment (DAT) with the half- inch depth than with any other mulch depth. Better weed control from use of recycled pellets probably results from two factors. First, the pellets are three times the density of the crumble product thus creating a greater barrier for weed seed germination under the mtlch. Second, the recycled waste paper pellets absorb approximately three times their weight in water within a few days after application. As water is absorbed the pellets swell, fonring an interlocked mat of bonded pellets, of which the surface becomes relatively smooth. Restlts from the fabric disk showed limited spurge control was obtained with any treatment. There was a seed placement effect at 30 DAT with spurge number and at 75 DAT with fresh weight where seed placement tinder the fabric resulted in less growth than seed placed on top of the fabric (see table). Spurge also emerged around the contain- ', \ 1 ,I /N /)C 11( u/I 1o ited er circumference and in the slit where the fabric disk fits around the plant. Seed placement affected spurge germi- nation at 30 DAT and spurge fresh weight at 75 DAT with the greatest amount of spurge occurring when seed were placed on top of non-Spinout treated fabric. Rout herbicide provided excellent spurge control. Recycled pellets continued to provide excellent spurge control after the plants were repotted in May 1996. With Girard's Rose azalea at 60 DAT recycled pellets provided greater spurge control (spurge number) than recycled crumble (1.0 vs 3.8), and the one-inch depth provided greater control than the half-inch depth (1.5 vs 3.3); data for Fashion azalea followed a similar trend. Both cultivars of azaleas Qrown with recycled waste paper mulch were generally similar in size to non- treated control plants and Rout-treated plants. No treatment produced a nega- tive effect on plant growth when com- !,a l n C1 l iCtS iol *cycled paper reat S ents on Girard's !(se. At 550 DAT r! I recycled paper t iaents effects (~ ~ cre similar with ^ 1 /' 7 1 i card's Rose to dIants grown with ,k :out and the non- ',) v 1 i cated control )Iants. When com- paring effects of recycled paper treat- ments on Fashion azalea at 240 DAT, crumble grown plants were similar at half and one-inch depths (22.4 vs 23.6). Plants grown with pellets were smaller at one inch than those grown at a half inch (19.5 vs 24.3). The pelleted mulch appeared to retain greater water than the crumble mulch. Since all treatments were watered similarly with overhead irriga- tion, the growth suppression with recycled pellets may be related to excess moisture. Fashion azalea at 550 DAT showed the only response to additional phosphorous (P). Those plants grown with P were larger than those without P. The pH of the waste paper pellets is 6.8 and crumble is 7.0. Medium solution pH gradually became more acidic with all treatments over the course of the study, ranging from 5.6 - 6.6 at seven DAT to 4.9 - 6.0 at 240 DAT. These levels are within acceptable ranges for container grown nursery crops. Soluble salts (seven and 30 DAT) were affected by additional P and mulch. At seven DAT, Alabanut Agriicultural Expeimuent .Station H-ighlights 1 U of Agriculturial ReschcI Vol. 44, No. 4, Winter 1997 Treatment 2 Pellet/su 5 Pellet/su Pellet/su Pellet/su Crumble/su Crumble/su Crumble/su Crumble/su Pellet/st 6 Pellet/st Crumble/st Crumble/st mulch depth seed placement phosphorus mulch depth mulch seed 8 mulch" P Depth P-level 3 (inches) (ppm) Initial Spurge Spurge #/pot fresh wt. 30 75 75 DAT 4 DAT DAT * NS NS Fabric disk/su Fabric disk/st Fabric disk+spin out/su Fabric disk+spin out/st fabric disk seed placement fabric disk'seed Rout 9 Control 10 NS NS NS " 0.0 3.5 0.0 12.0 20.5 26.8 'Plants were repotted May 7, 1996, and retreated. 2 Only significant affects were included in the statistical model statement. 3P source was triple superphosphate; mg L- I (ppm) based on pounds of r 4 DAT = days after treatment 5 su = seed applied under the mulch Est = seed applied on top of the mulch 7 Treatment not included 8 Mulch/seed interaction based on 25 mm depth only. 9 Rout 3G herbicide applied at three pounds a.i. per acre. 10 Non-mulched control Mulch Control of Prostrate Spurge in Container Smith is a former Research Assistant and Giiam is a Professor of Hart culture; Edwards is a USDA Agronomist; and Olive is Superintenoent of the Ornamental Horticulture Substat on. Alabamia Agricultural Experiment Station Highlights of Agricultural Research Vol. 44, No. 4, Winter 1997 pellets \with added P had Grown Plants medium solution soluble salt After repotting' levels of about 2.0 s/mmhos. Spurge Spurge Spurge Pellets with no P and crumble #/pot #/pot fresh wt with added P and no P had sol- 30 60 60 uble salt levels of 0.87, 0.88, DAT DAT and 0.46 s/in, respectively. A similar trend occurred at 30 0.25 2.3 3.1 DAT; however, medium solu 0.37 1.4 10.6 tion salt levels had dropped. 0.0 0.0 0.0 rn 0.0 0.25 0.03 ranging from 0.43 to 0.26 s/m. 1.9 4.0 5.6 Research indicates 5.5 5.5 23.0 recycled waste paper in the 1.4 2.0 3.5 pelleted form provides superi- 2.5 3.6 56.2 or weed control compared to - - the crumble form. The one- inch depth is necessary to pro- vide adequate weed control. * **. Repotting and reapplying the NS NS mulch to three-gallon contain- N . er-grown azaleas had no NS * apparent negative effect on NS NS NS azalea growth at any time dur- NS . ing the study. While plant quality was not rated, plant appearance for all plants was reflected in good foliar color. Two environmental issues are addressed with the use of recycled waste paper: a - reduction in chemical use to 0.25 1.6 9.5 control weeds and an alterna- 5.3 8. 59.1 tive application for a post con- sumer by-product that would otherwise be disposed of in ecycled paper per pot. landfills. Is PLAN1ING BEFORE MHR sC-/o Y Lee Norfleet, Wayne Reeves, Chiarles iuine ste, and Dale Monks V 1*, .4 JIa A" H,v4lilrts of A~ricutural Research 1Io/. 44, NVo. 4, Whiter 1997 AMA P 3 Y OTTON GROWERS in northern Alabama are challenged by a limited growing season in which to make a profitable crop. Although growers are aware of recent AAES research that demonstrates the benefit of using small grain cover crops with no- tillage, this system can increase management demands of the grower. Farmers are faced with the dilemma of producing sufficient cover crop residues to improve soil quality and conserve soil water but still manage to plant large acreages in a timely manner so that the cotton has sufficient time to produce a crop before fall frosts. Recent USDA and AAES research provides useful information for growers to make a better informed decision regarding this challenge. Producers who use a winter cover crop as a conservation practice and to reduce compaction in no-till and conventional tillage systems usu- ally kill the cover in late February to mid March. This prevents cover crops from producing large amounts of bio- mass necessary to provide weed con- trol, moisture conservation, and to maintain or improve topsoil. USDA and AAES researchers have found that for cotton growers in North Alabama to realize the full benefit of cover crops, they need to utilize weather and soil climate data and plant by the ther- mometer and not the calendar. Long-term weather data, criti- cal cotton growth stages (see Table 1). and a computer program designed to generate long-term estimates of cli- mate and crop growth from past data were used in this study to develop optimum planting dates for cotton in the Tennessee Valley. The combination of well established cotton physiology data with average climate and soil temperature illustrates: (1) how late cotton can be planted and still have enough days to mature: (2) how early planting may cause poor germination and seedling dis- ease: (3) synchronization of planting date with seasonal rainfall and critical growth periods: and (4) the benefits of using cover crops and the ability for letting cover crops grow longer into spring without jeopardizing optimal planting dates. The long-term weather data was generated by the Erosion Productivity Impact Calculator (EPIC) program. This program uses measured weather data from established stations and statistically generates weather pat- terns for 100 or more years. Periods of drought. intense rainfall. and abnormal temperatures are all estimated based on their past occurrences. Stations located in Muscle Shoals, Huntsville, and Bankhead Locks in Alabama sup- plied the weather data for this research. The daily average for soil temperature, maximum and minimum air temperature, rainfall, and root zone soil moisture was generated for a 100- year period in North Alabama from these locations. This data was used to develop average dates of frost (see Table 2), soil temperature at four inch- es, weekly rainfall patterns (see the figure). and growing degree days (DD60s). Dewey and Decatur silt loam soils were used in the simula- tions. Cotton's base temperature for growth is 60"F. Below this tempera- ture, plant growth is hampered and seedlings tend not to germinate. Daily heat units or DD60s are calculated by Cotton Planting continued on page 16 Alabama Agricultural E\periment Station Highlights ofAgricultural Research Vol. 44, No. 4, Winter 1997 Cotton Planting, continued from page 15 adding the maximum and minimum temperatures for each day, dividing h\ two, and subtracting the base tempe a- ture of 60')F. For example: I(86max + 60mmin) / 21 60base = 13 DD6Os. Once planted, cotton germi nates readily under favorable moisture conditions and temperatures above 60?F. Research from Texas in the 1960s reported a 10-day average soil temperature above 60oF is needed before the start of planting. Lower soil temperatures had emergence rates ol less than 40%. The 10-day average rule of thumb has since been used success fully for many years. Research in Mississippi showed an average tem- perature of 68"F was optimum for a good rate of' germination. Other studies have found three-day axerages of 65?F to be an optimum temperature to begin planting. Table 2 shos that for the 60? rule, planting should not start until aftei Apiil 10 in the Tennessee Valley and the probability for optimum tem- peratures for planting doesn't occur until after May I After planting. 50 DD60s are necessary for seedling emergence. With soil temperatures approaching 70OF and adequate moisture, eier- gence may occur in five to six days. Soil temperatures nearer 60?'F may cause emeigence to take 15 days or more due to the sloxer accumulation of DI)60s. Delayed emergence affects plant stands and yield. Stidies have shown survival rates of seedlings that emerged on the fifth, eighth, and twelfth day alter planting to be 87. 70. and 301(r, respectively, corresponding Table I. Estimated Minimum DD6Os Required for Selected Development Stages for Selected Variety Types I Development landmark Very early Early Medium Germination 50 50 50 Planting to Ist square 50 (350) 400 (400) 400 (400) Ist square to early bloom 350 (700) 400 (800) 400 (800) Early bloom to cutout 350 (1,050) 450 (1,250) 550 (1,350) Cutout to harvest 500 (1.550) 500 (1,750) 500 (1,850) Information compliments of Dr. David Guthrie, Stoneville Pedigreed Seed Company, Stoneville, MS. Number in ( ) is cumulative DD6O total. Table 2. I 00-Year Simulated Average Dates Using the EPIC Program on Conventionally Tilled Decatur Silt Loam' Temperature benchmark Last spring frost First day of positive DD6Os First day DD6O >10 Soil temperatures at 4 inches 10-day average >60 0 F begins 4 days > 62 0 F begins 3 days > 65 0 F begins Date April 4 April I April 7 April 10 April 10 May I Optimum germination temperature 680 F >3 days begins May 4 First fall frost Oct. 30 1 Corresponds with published data from extension, NRCS soil survey reports, and other lit- erature. to relatixe yields of 100. 46. and 29%. Others have shown field emergence to be 50. 72. and 77%. xhen 10. 20. and 30 DD6Os accumulated in the first five days alter planting. On axerage in North Alabama. 10 DD6Os do not occur until April 7. 30 DI)60s do not accumulate until April 22, and 50 DD6s. the optimum required for rapid emergence. do not occur until May i. The Average Weekly Rainfall chart for 100-year simulations indi- cates a rainy period normally occurs in late June and early July (see figure). Depending on cultivar, it takes 700 to 800 DD6Os to reach the bloom period (see Table I). Peak bloom is the most critical period for water requirement and Iirst Iflower signals the beginning of a rapid rise in the need for Moisture. By planting around the first of May or xhen soil temperature axerages 650. the cotton plant can still develop its eamrly blooms in time xith these sum- mer rains since on axerage 700 to 800 DD60s do not accumulate until this early July period. Moisture reserves from spring rains are normally ade- quate until the summer rains arrive especially if past residues are managed and coxer crops used. The end of effectixe bloom is calculated by subtracting 750 DD6Os (amount needed to mature a boll) from the average date of Iirst 32?F freeze. Aig. 16 is about 750 DD6Os before the average date of first fall frost on Oct. 30. allowing the last bolls to develop. Total DD60s accu- mulated before harvest increases to around 2,000 instead of the values in Table I die to temperature and mois- ture stresses slowing development and "wasting" DD6Os during the bloom period. A Ilaama Agr'iculItual xLperimienr .Stationi Highlights of Agricultual R.serch Vol. 44, No. 4, Wineor 1997 Aug. 16 Cutout Rainfall, in. 1.8 1.6 1.4 1.2 I.0 0.8 0.7 0.6 0.5 0.4 0.2 0 Apr. I I lay I May 31 June 30 July 30 h I 1, r' i: K ~ Ru lute Junie uijit erk hi/ For the cotton plant to optimal- ly produce during this period (first bloom to Aug. 16), 0.3 inch of water daily or 2.1 inches per week are needed to prevent any moisture stress. The rain- fall chart shows that 0.7 to 1.5 inches per week are from summer rains: unless irrigated, the rest must come from water stored in the soil and that is if all rain goes into the soil and is then available to the plant. Therefore, management practices to control runoff and increase soil organic matter and available water holding capacity are vital to overcom- ing this shortfall. The best way to con- trol runoff and increase soil organic matter is through the use of cover crops, regardless of the amount of tillage. In conservation tilled systems, research at the Tennessee Valley Substation in Belle Mina has shown that cover crops ameliorate the compaction problems inherent in North Alabama soils. In addition, research has shown yield increases and improved weed control through the use of properly managed winter cover. Aug. 29 Sept. 28 O illi( Ohl~~ I cli 011 pci/w 11, Killing the cover crop in February or early March does not allow the crop to get the early spring growth spurt from the rising tempera- tures of March and early April. Empirical data and EPIC simulations show that covers killed at this time yield only about 1,500 pounds per acre biomass and give about 50% coverage. A 100-year simulation of a winter rye cover showed that by moving the cot- ton planting date to late April or early May and killing the cover crop three weeks prior to planting, residue inputs from cover crops can double. These simulations correspond well with research conducted at the Tennessee Valley Substation and as much as 4,500 pounds residue dry matter per acre can be expected in North Alabama with this management scheme. Weather and soil climate data simulated for 100 years indicate plant- ing cotton in the Tennessee Valley before May 1 may be risky. Cotton growers should plant by the ther- June 20 Early season Alabama Agricultural Experiment Station Highlights of Agricultural Research Vol. 44, No. 4, Winter 1997 mometer. not the calendar. Low soil temperatures and slow accumulation of grow- ing degree days (DD60s) can cause yield reductions from poor germination and disease. Soil conditions tend to be optimum for germina- tion around late April to early May. By delaying the planting date a couple of weeks or more from the Ct. 28 regional norm of April 15, growers are able to get the , r full benefit of their cover crop dollar with biomass production doubling when the cover grows through March. Planting when soil tempera- tures are around 65 0 F allows for rapid germination and cotton reaches its effective bloom period in time for the normal summer rainfall peaks, which tend to occur in late June and early July. This later planting date still gives the plant enough DD60s to mature before the first frost (Oct. 30). Additional measures to ensure boll maturation include using early matur- ing varieties, managing to reduce stress from nutrient deficiencies and insect control, and reducing drought stress by increasing soil water storage and availability with conservation sys- tems leaving adequate residue from cover crops. Norfleet is a Soil Scientist of USDA- NRCS Soil Quality Institute; Reeves is an Agronomist of USDA ARS NSDL; Burmester is an Extension Research Cotton Specialist; and Monks is an Associate Professor of Agronomy and Soils. June 26 Full season _ Lee Camlpbell, Bill M/ossx, Jim11 Pitts, Bobbv Booze, Jim Buanoon, and Mark Wilson actci ial spot, canscd by Ayunt/u n1 no o/NA rnh.1i h. /rut, Is a serious disease of peach that affects leaves, txxis~s, and fruit. This disease may cause sex ere defoliation, wxhich wxill reduce fruit size and wxill weaken the tree if' it occurs early in the summer. The most serious economic impact results from fruit infection, which my render the entire crosp LIumarketable in years wshen bacterial spot is severe-. CGA-245704 induces systemic resis- tance in the plant by acti- Mtin(C natural defense mechanisms that result in disease control. CGA- '45704 is beine tested for bacterial spot in peaches hecause copper bactericides haxve been relatixely ineffective in controlling bactei al spot, since they are limited to dormant or early season use because of AAES researchers have ob- tained moderate levels of' contirof of bacterial spot on peaches using an experimental product CGA-245704, xxhich is currently being dexveloped by Nov artis Crop Protection Inc. Bacterial spot occurs in the United States in all peach groxwing icgions east of' the Mississippi Rix er but is more prevalent in areas where the environment is warm and humid. such as Alabama. Cultiv ars introduced into the Southeast f'rom Calif orni a (where bacterial spot does not occur). especially the cultivar O'Henry. are most susceptible to bacterial spot. Prev ious AAES research has shoxwn that the use of some common fungi- cides 11ax cxen incirease incidence of bactei al ,)O( on ,uisecptible cultixa, Treatment Disease rating ph\ totoxicil>. Field tirials wxere conductcd at the ChilIton Area H-orticulture Sub- station ( CAH S) in Clanton and the F. V. Smith Resear ch ('enter i I s) in Shoirteir in the sulniie O1 190- P'each Reduction Infected fruit 2 Reduction Nontreated control 2.56 -97.2- CGA-245704 1.98 23.0 74.4 24.2 Ratings were made from 25 fruit per replicate (250 fruit) and based on 1 (<25%o surface covered) ;2 (26-50%o); 3 (51- 75%); 4 (>75%o). 2 Represents the number of fruit on which lesions appeared. Higligh'lts of Agic'hu1;,,,' Researc Ii/W. 44. No. 4, Witer' 1997 Table I. Severity and Incidence of Bacterial Spot on Fruit Iaio ~~ o/ i prcHi Ii on oulii4 iiit o4 iru i () I'Hi cultivar O'Henry was used at both locations since any product that pro- vides moderate spot control on this cultivar likely will give excellent spot control on less susceptible cultivars. During the trial, daytime tempera- tures averaged 79.9 0 F at EVS and 78.2 t F at CAHS and rainfall was 19.3 inches at EVS and 23.3 inches at CAHS. CGA-245704 was applied to peach foliage weekly at recommended rates (0.24 pounds active ingredient per acre) beginning at first leaf bud break and continuing to fruit harvest. Thirteen applications were made to leaves and young developing fruit. Disease inci- dence and severitx ratimles wrci e made on \la 29. Jlk 5 5. and June 27 at 5. July 3. and "x JuIy 9 at EVS. .e\ Serity ratings rcpiesent the mean number of lesions per leaf and were based on a sample otf 30 leaves per replicate with live replications. Tres in lield trials at CAHS were bearing fruit for the first time and trees at EVS were not yet bearing. Twenty-five fruit per replicate per treatment were harvested on July 1 at CAHS. Ratings were based oi the percentage of fruit surface covered by lesions: I = less than 25(/c of friuit sur- face covered. 2 = 26-50%/c covered. 3 = 51-75%o covered, and 4 = greater than 7517 covered. Only frtit in category I would be considered marketable. Disease severity ratings on foliage showed that over three sampling periods CGA-245704 significantly reduced severity ot bacterial spot com- pared to the nontreated control. This was also reflected in the friuit ratings where 29 c of the infected fruit was rated I in the CGA-245704 treatment conlpared to the hint! eated control in which only 4% ot the inected fruit had a rating ot one. Hence, the ise of CGA- 245704 resulted in 25%- more mar- ketable fruit in this trial. These resilts show that CGA- 245704 provides partial control of bac- terial spot. This finding is consistent with the results of an independent study in North Carolina in which CGA- 245704 reduced tie incidence of spot on fruit and foliage in moderately sus ceptible cultivars (D.F. Ritchie. NCSU). Based on preliminary AAES research results. CGA-245704 offers hope that this disease may be control- lable. allowing the introduction of new California varieties. Ongoing research will assess the benefits of combining CGA-245704 with oxytetracycline (Mycoshieldi"') on spot incidence and severity. and on weight and number of marketable frtit. It is hoped that when this product is available on the U.S. mar- ket, researchers will have established the appropriate rate and frequency of appli- cation to be used by peach growers. Campbell is a Researcr Spec al st and Moss s a Graduate Student of Plart Pathology; Ptts s Superintendent and Boozer is Area Horticuturist at the Chiton Area Hoirt culture Substation; Bannon is Director at the E.V Smith Research Centei; and Wilson i Assistant Professor of Plant Table 2. Severity of Bacterial Spot on Foliage Test I- CAHS Test 2- EVS Disease Disease Disease Disease Disease Disease severity severity severity severity severity severity rating #1 rating #2 rating #3 rating #I rating #2 rating #3 Treatment Mean' Reduction Mean Reduction Mean Reduction Mean Reduction Mean Reduction Mean Reduction Pct. Pct. Pct. Pct. Pct. Pct. iNontreated i - 2.2 2.4 _ CGA-245704 1.6 16.0 1.5 43.2 1.6 9.5 1 Represents the mean number of lesions per leaf from 30 leaves per replicate row. Alabama Airic ultual I- \pe ruimen Station Highli(=hts of Agricultura l Research Vol. 44, No. 4, Winute, 1997 2.4 - 2.1 .9 25.6 1.7 3.0 28.1 20 espiration Patterns Play Key Role in Pest Biology Can you hold your breath for two hours? Some ticks can! Can you hold your breath for even. 15 minutes. w Fire ants can, and even longer! Many insects and other arthropods such as ticks exhibit a discontinuous pattern of respiration. From the animal's perspective, peri- odic release of respiratory gases decreases the amount of body water lost during exhalation and aids respi- ration in high carbon dioxide, low oxygen nests and tunnels. Of partic- ular interest from a pest control per- spective. periodic respiration can prevent rapid inhalation of fumi- gants and other insecticides. Respiration patterns of the beetle cockroach. Diploptcra pu- tata. and red imported fire ant. Solenopsi.s iin'ictc, were examined using flow-through respirometry methods. Insects were placed into the rspirometry system and allowed to acclimate for 10-30 minutes before each recording. To vary tem- perature. the respirometry chamber was placed into a comput- er-controlled incubator. Dry, carbon dioxide-free air was pulled through a respirometry chamber containing the insect and into a carbon dioxide ana- lyzer. Air flow was regulated with a mass-fow controller and the con- centration of carbon dioxide in the air stream was recorded at one sec- ond intervals with a computer. Discontinuous gas exchange can be broken down into three dis- tinct phases. During the closed phase, the insect is not releasing any carbon dioxide (Figure 1. Point A). Following the closed phase, some carbon dioxide escapes from the insect (Figure 1. Point B). It is dur- ing this time that the insect is taking oxygen into the body and the oxy- gen fiowing in effectively blocks water from escaping the body result- ing in greater water economy for the insect. Finally the insect releases a burst of carbon dioxide (burst phase Figure I. Point C) and the cycle repeats itself. For the beetle cock- roach. the interburst phase at room temperature (about 77oF or 25oC) lasts up to five minutes. Interest- ingly. only motionless cockroaches that assume a resting posture respire discontinuously. The interburst peri- od of the red imported fire ant is temperature sensitive (Figure 2) and ranged from about 40 minutes at 50oF ( 0oC) to almost one minute at I04oF (400C). Respiration patterns of native subterranean termites ReticiIiteites sp. and the Formosan subterranean termite. Coptote rnes Jorna'uiius, have also been exam- ined. At room temperature, workers and soldiers respire continuously (Fiuure 3). These results are interest- ing because subterranean termites live in closed nests with low levels of oxygen and high concentrations of carbon dioxide: exactly the condi- Alabamai Agriculturaul xPEerinieni .S'tation Hilihts of/Agicu Ihltural/ ReseacuII Vol. 44. No. 4, inlteCr 1997 77--- JLg) A. G. Appel, J. T VoL't, and 7. G. Shelton Fig'ur 1. Bl, t stan itite but f per1iodlt 4 Uf u II H l. u Icr u V't~a tions tor which the discontinuous pattern is thought to be adaptive. These studies have found discontinuous gas exchange pat- terns in a variety of important pests including cockroaches, fleas, red imported fire ants, and several other species. The presence of dis- continuous gas exchange in pest species may help to explain control failures when fumigants and other volatile insecticides are used. Further research by AAES person- nel has demonstrated that exposure to contact insecticides eliminates the discontinuous pattern of respi- ration making the insect more sus- ceptible to desiccation and possibly easier to control. These studies highlight the importance of under- standing the basic biology and physiology of pest species to advance modern pest control. Appel is a Professor ano Vogt an( are Grauate Research A ssta Departmrent of Entomology. Sheeto in th / i Iu,? nterbin t pt'ruid d, crease with incre i i. /~~i i iotn~rr U ir i igr'ie 3. Contiituous retp iI(tioll /)tt&Irn inl eatr cit/l t/Icc ic//ic cc/ tnt cc/i /," cu Alanbamai Agricttltorl Experient Station H-igh~Ilig~hts t4Ag'ri(Iulhral Research Vol. 44, No. 4, Winter 1997 ETLANDS IMPROVE EFFLUENT QUALITY FROM A CHANNEL CATFISH INJTENSVF Gt TTL [ E SYSTEM Stanislaus% Son,,cho/,c,: h'viing~ H. Yoo, Michael P Ma vsei; John Martin, aiid Michael Wi/c a c ~ / 5 6 ( / / / , t' *-~. .- 9 -. + .. . ..... > j a. . .:6c ,~ as1 41. '1 . .r : + > . . + s" . tr. ;. Alabthn ta Agr~'ictua F__i (1/Iperimiiii Sit hun I-i,,i, 4 /isii o/ A g' iluuat Resarc/i Vol. 44. No. 4, Wit , 1997 v, i ~ :4' 48, r. / -4+ OST CATFISH CULTURE effluents are discharged without previous treatment, prompting increasing environmental concerns due to the potential impact on receiving waters. Constructed wetlands have become popular as an effective technique to abate pollution from agricultural sources. The similarity of the fish waste constituents to other agricultural wastes suggest that constructed wetlands can be used to treat fish effluents. Current research at Auburn University's Fisheries Station show that catfish effluents from an intensive culture system called in-pond raceway (IPR) can efficiently be treated with constructed wetlands. Water quality impairment in aquaculture systems is driven primari- ly by feed input. Nitroge, phospho- rus, and organic matter contained in noneaten feed and feces accumulate during the grow-out period. These nutrients can cause oxer-fertilization, or eutrophication, of nearby streams, ;2 L 5/Ic)ifl~cono/ .+et-ut4 o 00 iu t e l LI l u i I r/U causing oxygen depletion, and subse- quently pollution problems. Researchers in the AAES have been studying a catfish culture system called IPR since 1991. The system produces fish at high densities, is adaptable to any type of pond, and construction characteristics allow easy feeding. observation, and harvesting. Probably the most remarkable feature of the IPR is the incorporation of a device at the end of the raceway that promotes settling of solid wastes before they enter the pond. Settled solids are then pumped into a treat- ment system. Constructed wetlands arc used to reduce the nutrients and organic matter from these effluents. Constructed wetlands can be conceived as a series of interactive components, i.e. water, substratum, microbial biota, flora, and fauna. Bacterial transformations and physico- chemical processes are considered the major mechanisms of pollutant removal in the system. Although plants can absorb large quantities of nutrients, plant uptake is only a temporary storage mechanism, since nutrients incorporat- ed in tissue are released back to the sys- tem after their death. The main role of vegetation is to provide a substrate for microbial growth and for transmission of oxygen through the air spaces of stems and leaves to the root zone. Excess oxygen not used by root respira- tion becomes available for microhial respiration, which is required to drive biochemical processes including oxida- tion and decomposition of organic mat- ter and nitrification. To evaluate the effectiveness of constructed \ etlands in treating IPR Wetlands, continued on page 24 Alabanma Agtricmiltura Experiument Station Highlights of Agricultural Research Vol. 44, No. 4, Winter 1997 Wetlands, cnntin1ueJ tram page 23 effluent, .t C O nine pkxv min hoc, tilled wxith gravel and planted wxith i tlher cattail /soft rush or wxater hy acinths wxas constructed. 1Txxo experiments wxere conducted dur ing .tune-September 1996 and 1997. Waici samples were collected on a we eklI basis fr om the inflowx and ouittloxx of each wetland system and chemicallIy analyzed to determine percent reduc- on in biological oxygen demand (BUD). total suspended solids (TSS), total nitrogen (TN), and total phospho- rus (IP). Each experiment had a con- trol box filled with grav el wxithout plants and the wxater is periodically recirculated for additional oxyg en suipply. Air entrainment occurred as bottom wxater reached the Surf ace. Water inlflowx in each wetland wxas 76 and 81 gallons per day lor 1996 and 1997. respectively. HyINdraulic reten- tion time wxas twxo day s in each wxet land sy stem. The percent reductioins in concentration of selected xxater- dual- BO D TSS TN TP Nonplanted Pct. 89.1 93.1 27.3 28.3 Wv. hyacinth Cattail/rush Pct. Pct. 94.8 94.4 94.9 96.2 68.5 60.7 60.7 60.9 tx pai ametCi, after the elu tent Vi'~ed through the wetlands are presented in the table. Nonplanted systems performed similar to planted sx stems in reducing BOD and TSS, but planted ,x etlands wxere more efficient in remov ing phos-~ phorus and nitrogen from the IPR el lu- ent. Reduction of total nitrogen in plant- ed xxwetlands iraimed betxccii 6(1 to 81'. as comipared to 27 to 67,4 inl noniplanted sxystems. Planted wxetlands remox ed txxo to 1 5 times more phosphorus than non- planted systems. Although most catf ish f armers in Alabama do not need di scharge permits under current ieulations. Nonplanted W. hyacinth Cattail/rush chanLcs in effluent reetiLtiomii aie expected in the future. I hercelore. studx'inig alternativxe cost-effectixve piro- duetion sN stems that minimi.'e impact on the receix ing, wxater qluality should be benelicial for the tutur-e success of' the cat fish i ndustrv. The LiSe of eon- structed xwetlands to treat fish prioduc- tion eflu ents is viable and effectivxe as suipported bthsstudy. Sorirenrio zner is a Graduate Researcri Assistant of Fisheries arid Allied Aquacultures:Yoo is an Associate Professor of Agicultural Engineering Massei is an Associate Pirofessor and Martin arid Wicox are Graduate Research Assistants of Fishhries aria Allied Aquacultures AL ABA\MA AGRICULITURAL LXPtERIINI STIA!ION AUBURN UIV t\ERSITY' AUBU1RN tUNIVEtRSITY ALAt BAMA 364')-m40i3 POSTMASTE R-Address Conmcionn Requesied 24 A Ia/ua i Agricultual (1 1 exitieci Station H-ighlightsm a/ A grmiuitnrl iscar t's o/. 4.4. N. 4. V iwer 1 9c7 Percent Reductions in Concentrations of Selected Water Quality Parameters After Constructed Wetlands