Report 30. The effects of alley cropping and other soil conservation practices on maize (Zea mays) yields over two years of cropping

Abstract

The effects of different soil conservation practices on crop and hedgerow biomass yields were assessed under lowland conditions in Haiti over a period of two years. The trial was conducted at Pernier (1300 mm annual rainfall) on a north-facing slope of 30%. The soil is a fine, mixed isohyperthermic Lithic Eutropept with pH = 8. Soil conservation structures spaced 4 m apart on contours were compared to a control without structure. The treatments tested were: stone walls; contour canals; alley cropping with hedgerows of Leucaena leucocephala; alley cropping with rows of Panicum maximum; hedgerows of L. leucocephala and P. maximum; alley cropping with fertilizer; control without structure. Two years after Leucaena was established, maize was planted two seasons per year. Plots with vegetative structures had 20% fewer maize plants than did other plots, but received prunings as mulch. Large differences in maise yields were recorded among the treatments over the four seasons: - During the first two cropping seasons, alley cropping gave lower yields than did other practices. From the third crop, alley cropping with fertilizer resulted in higher yields than conventional practices. - In the fourth season, alley cropping with Leucaena, with or without fertilizer, gave higher maize yields than all other practices despite the loss of land area of the hedgerows. Stone wall, contour canals and grass rows gave the same yield as the control without structure. - Maize yields steadily decline in absence of alley cropping while yields with alley cropping remain stable or increase over time. - Use of moderate amount of fertilizer in combination with hedgerows increased maize yields from the second cropping season. - Grass rows supply much less biomass to serve as mulch than does Leucaena. Comparisons Among Alley Cropping Treatments: - Hedgerows and fertilizer yielded consistently more maize grain than hedgerow with grass and hedgerow alone treatments in all four seasons. - The combination of Leucaena hedgerow with grass resulted in higher maize grain and biomass yields than hedgerow alone over the four seaons - In terms of biomass yields, Leucaena hedgerow with grass was the most productive followed by the hedgerow and fertilizer treatment in all seasons. Implications and Recommendations: - Under proper management, alley cropping, with or without fertilizer, maintains crop yields over time. - Stone walls, contour canals and grass rows are effective in reducing soil erosion, but to sustain crop yields, should be combined with practices that enhance soil organic matter and fertility. - This trial should be continued for more seasons to confirm trends observed in the third and fourth seasons. - Economic analysis should be conducted on the effect of combining grass with leucaena hedgerows to determine if the apparent additional crop and biomass yields merit the additional costs of planting and maintaining the grass rows. - Economic analysis should be conducted on the effect of fertilizer application in conjunction with soil conservation practices such as alley cropping. - Additional research is justified on alley cropping and other conservation practices that return substantial amounts of nitrogen rich biomass to the soil. - The effect of organic applications on phosphorous fixation in calcareous soil should be studied.

Objektif etid sa-a se konpare efè kèk pratik konsèvasyon sòl genyen sou pwodiksyon kilti ak pwodiksyon ranp lesena nan kondisyon peyi Dayiti sou yon perioòd de (2) lane. Etid la te realize nan Pènye. Sit la se yon tè pandye nan direksyon nò (30 % pant) ki resvwa 1300 mm lapli chak ane. Sòl la se yon tè fen ki gen yon pH = 8. Plisyè teknik konsèvasyon (estrikti yo gen yon distans 4 m ki separe yo) te kompare ak yon temwen ki pa gen estrikti. Tecknik sa yo se te: misèk; kanal kontou; ranp lesena (Leucaena leuocephala) tou sèl; ranp graminé (Panicum maximum); ranp lesena ak graminé; ranp lesena ak angrè; temwen san estrikti. Mayi a te plante de (2) fwa chak ane, de (2) lane apre ranp lesena yo te enstale. Nan pasèl ki gen ranp yo, mwens mayi te simen (20% mwens) pase nan lot pasèl yo. Fèy ak branch vèt ki koupe nan ranp yo te simen nan mitan ranp yo. Nou konstate gwo diferans nan randman mayi pou divès teknik yo: - Nan de (2) premye sezon yo, teknik ranp vivan ak lesena te bay mwens randman mayi pase lòt teknik yo. - Nan katryèm sezon an, randman mayi nan mitan ranp lesena yo, avèk oubyen san angrè, te depase randaman tout lòt teknik yo malgre te gen mwens pie mayi nan mitan ranp yo. Misèk, kanal kontou, ranp graminé yo te bay menm randman ak temwen an ki pa gen estrikti. - Nan kote ki pa gen ranp lesena, randman mayi a te bese apre chak sezon. Nan mitan ranp lesena yo, randman mayi a te ogmante apre chak sezon. - Lè nou itilize yon ti kantite angrè nan mitan ranp lesena yo, randman mayi a te ogmante plis apre chak sezon. - Ranp graminé yo te bay mwens randman biomas pase ranp lesena yo. Konparezon ant Ranp Lesena - Nan tout kat (4) sezon yo randman mayi nan ranp lesena ki te gen angrè a te pi plis ke nan lòt ranp lesena yo (lesena ak graminé, lesena tou sèl). - Ranp lesena ak graminé a podwi plis mayi ak plis biomas ke ranp lesena tou sèl la nan tout kat (4) sezon yo. - Pou pwodiksyon biomas ranp yo, se pasèl lesena ak graminé a ki te podwi plis biomass. Pasèl lesena ak angrè a te vini apre li nan tout sezon yo. Rekòmandasyon - Itilizasyon ak bon jerans ranp lesena avèk oubyen san angrè pèmèt bon jan pwodiksyon pou plis tan. - Misèk, kanal kontou, ranp gramine bon pou kenbe tè men teknik sa yo pa pèmèt pwodiksyon kilti kenbe lontan si yo pa asosye ak lòt teknik ki ka amelyore kantite matyè òganik ak fètilite tè-a. - Travay sa-a dwe kontinye pou bon jan konfimasyon rezilta twazyèm ak katryèm sezon yo. - Analiz ekonomik ta dwe fèt nan ka lesena asosye ak graminé a pou wè si kantite depans pou enstalasyon ak travay anplis graminé a jistifye pou ogmantasyon randman pasèl la bay. - Analiz ekonomik ta dwe fèt tou sou efè angrè a pa rapò a teknik ranp lesena san itilizasyon angrè. - Lòt etid nesesè sou ranp vivan ak lòt teknik konsèvasyon ki ka pòte pi bon amelyorasyon nan kalite tè a. - Efè aplikasyon matyè òganik sou jan tè kalkè yo kapte fosfò nan sòl la ta merite etidye tou.