Alley Cropping System Research Articles

Decomposition- and nitrogen-mineralization patterns of Leucaena leucocephala and Cassia siamea mulch under tropical semiarid conditions in Kenya

In agroforestry systems, loppings from trees and shrubs are commonly used, often as mulch, as sources of nutrients for interplanted crops. Therefore, it is important to understand the rates of mulch decomposition. This paper reports the results of a study on the decomposition and nitrogen (N)-mineralization patterns of the leaves, small twigs, and mulch (leaves plus twigs) of Leucaena leucocephala and Cassia siamea in a field experiment in an Alfisol in semiarid Kenya. Plant materials contained in 5mm nylon bags were placed below or on the soil surface in an alleycropping system involving the two tree species, with maize (Zea mays L.) as the intercrop. For plant materials of both species (except Leucaena leaves), there were two phases of decompositions: an initial rapid phase and a slower second one; Leucaena leaves had only a single phase. When placed below the soil surface, the decomposition rates of both Leucaena and Cassia mulch were similar (about 12% week-1 in the first phase and 1% week-1 in the second phase). When placed on the soil surface, Leucaena mulch decomposed 1.3 times more rapidly than Cassia mulch in the first phase. The patterns of N release from the mulch of both species were similar to those of mass loss. In general, mulch-decomposition and N-release rates of both species were related more to their C:N ratios than to polyphenol contents; while C:N ratio predicted the rate of first (rapid) phase, the rate of the second (slow) phase appeared to be regulated by lignin and polyphenol contents.

Competition Effects between Leucaena and Maize Grown Simultaneously in an Alley Cropping System in Sub-tropical Australia

SUMMARYA field experiment was conducted to assess the effect of competition between a leucaena hybrid and maize (Zea mays L.) when planted simultaneously in an alley cropping system. The leucaena hybrid (a cross between L. diversifolia and L. leucocephala) was planted at hedgerow spacings of 3 and 5.25 m, while maize was planted in rows 75 cm apart between the hedgerows. The spacing between the leucaena hedgerow and maize was varied by removal of 0, l or 2 rows of maize to give three spacing treatments of 37.5, 75 or 112.5 cm between leucaena and maize. A control plot of leucaena alone was also included in the treatments. The growth and yield of individual maize rows were virtually unaffected by the presence of leucaena, but maize had a significant influence on the growth and yield of leucaena. At full maize canopy development, photosynthetically active radiation reaching the leucaena was reduced in all treatments, resulting in a 75% yield reduction in leucaena at the closest spacing. Overall, maize grain yield reached 10.3 t ha−1 in the continuous maize plots (37.5 cm treatment). This was reduced by up to 40% after removal of two maize rows in the closest leucaena row spacing treatment. The implications of these results for the practical establishment of leucaena hedgerows with a maize crop are discussed.

Effects of Alley Cropping Systems on Soil Erosion and Soil Chemical Properties

Effects of Alley Cropping Systems on Soil Erosion and Soil Chemical Properties

Above- and below-ground biomass dynamics in a sole cropping and an alley cropping system withGliricidia sepium in the semi-deciduous rainforest zone of West Africa

A considerable amount of data is available about above-ground biomass production and turnover in tropical agroforestry systems, but quantitative information concerning root turnover is lacking. Above- and below-ground biomass dynamics were studied during one year in an alley cropping system withGliricidia sepium and a sole cropping system, on aPlinthic Lixisol in the semi-deciduous rainforest zone of the Cote d'Ivoire. Field crops were maize and groundnut. Live root mass was higher in agroforestry than in sole cropping during most of the study period. This was partly due to increased crop and weed root development and partly to the presence of the hedgerow roots. Fine root production was higher in the alleys and lower under the hedgerows compared to the sole cropping plots. Considering the whole plot area, root production in agroforestry and sole cropping systems was approximatly similar with 1000–1100 kg ha−1 (dry matter with 45% C) in 0–50 cm depth; about 55% of this root production occured in the top 10 cm. Potential sources of error of the calculation method are discussed on the basis of the compartment flow model. Above-ground biomass production was 11.1 Mg ha−1 in sole cropping and 13.6 Mg ha−1 in alley cropping, of which 4.3 Mg ha−1 were hedgerow prunings. The input of hedgerow root biomass into the soil was limited by the low root mass ofGliricidia as compared to other tree species, and by the decrease of live root mass of hedgerows and associated perennial weeds during the cropping season, presumably as a result of frequent shoot pruning.

Agroforestry opportunities for the United States of America

Agriculture in the United States makes intensive use of large portions, of the nation's arable landscape. This landscape is dominated by large fields of annual crops with few perennial buffering communities within them. Agroforestry systems such as riparian buffers, alleycropping, windbreaks, tree/pasture systems, and forest farming provide buffering opportunities within these landscapes. Riparian buffers and alleycropping systems provide two unique opportunities toward sustainable production by reducing nonpoint source pollution while increasing ecological diversity. The major impediment to agroforestry in the United States is a lack of identity. Agroforestry as a practice is not officially recognized by federal and most state agencies and thus does not qualify for cost-share support or funding for research and establishment of demonstrations. A recent white paper, prepared by representatives from government agencies, academic institutions, and nongovernment organizations, identified eight major actions that could provide the support, for making agroforestry an acceptable alternative to nonsustainable agriculture. Ames, Iowa. Project No. 3209.

Productivity of alley farming with leucaena (Leucaena leucocephala Lam. de Wit) and Napier grass (Pennisetum purpureum K. Schum) in coastal lowland Kenya

Inadequate supply of fodder is a serious constraint to the potentially-promising small-holder-dairy production system in coastal Kenya. Alley farming could be an approach to addressing this problem. A study of forage production based on Napier grass and leucaena in an alley cropping system was conducted on an infertile sandy soil in lowland coastal Kenya. The effects of leucaena hedgerows,Clitoria ternatea (L.) intercropping, addition of slurry (110 t ha−1 yr−1) and two harvesting managements (severe and lenient) on the yield of Napier grass fodder, were assessed. The study was initiated in 1989 and three years results are reported.

Nutrient dynamics during the first three years of an alleycropping agroecosystem in southern USA

An alleycropping system (AC), usingAlbizia julibrissin as the tree species, was compared to an annual legume-based cropping system (NA) over a three-year period. In both AC and NA, a crop rotation was implemented with the following sequence:Mucuna deering iana, Trifolium incarnatum, Sorghum bicolor, Triticale aestivum, andSorghum bicolor.

Growth and fodder yield of the Gliricidia sepium provenances in alley cropping system in dryland farming area in Bali, Indonesia

Growth and fodder yield of the Gliricidia sepium provenances in alley cropping system in dryland farming area in Bali, Indonesia

The effect of vesicular-arbuscular mycorrhizal inoculation on nutrient uptake and yield of alley-cropped cassava in a degraded Alfisol of southwestern Nigeria

Leaf and root (tuber) nutrient uptake patterns of cassava (Manihot esculenta Crantz) alley-cropped with gliricidia (Gliricidia sepium), leucaena (Leucaena leucocephala), and senna [(Senna (syn. Cassia) siamea] as influenced by vesicular-arbuscular mycorrhizal (VAM) inoculation in a degraded Alfisol were investigated in consecutive years. The cassava plants were mulched with fresh prunings of each hedgerow tree species at 2-month intervals in the second and third years of alley cropping. While VAM inoculation significantly influenced the root uptake of nutrients, the leaf uptake was not affected except for the uptake of P. In most cases, there was no difference in the nutrient concentration between inoculated and uninoculated plants, either in the leaf or in the root, indicating that the productivity of cassava was regulated by the amount of nutrients the roots could absorb. In spite of similar total soil N in all inoculated and uninoculated alley-cropped cassava plots and similar exchange-able soil K contents in inoculated and uninoculated alley-cropped cassava plots with leucaena and senna, greater uptake of N, P, and K and greater concentrations of K were observed in roots of inoculated alley-cropped cassava with gliricidia and leucaena than with senna. These results indicated that greater mineralization and availability of nutrients to cassava roots from prunings of nodulating gliricidia and leucaena than from non-nodulating senna may be important, particularly with efficient VAM inoculation, in these alley-cropping systems. Also, for similar nutrients in the inoculated and uninoculated cassava soils alley-cropped with each hedgerow species, VAM inoculation significantly enhanced cassava root dry weights, indicating that an effective VAM fungus can be an agent of greater nutrient uptake in a competitive environment.

Impact of rainfall regime on the decomposition of leaf litter with contrasting quality under subhumid tropical conditions

In alley-cropping systems, hedgerow trees are regularly cut back. Losses of N released from the decomposing prunings are minimized when N release is synchronized with crop N demand. In this study, the sensitivity of the decomposition of Leucaena leucocephala, Senna siamea, and Dactyladenia barteri leaf litter to the nature of the rainfall regime is correlated with the residue quality. The litterbag technique was used to measure decomposition. Four periods of 115 days, each starting at a time when hedgerow trees are normally pruned, were selected and the rain that fell during each of these periods in 1986 was simulated on a day-to-day basis by applying irrigation water on the litterbags. The number of rainfall events was better correlated with the percentage dry matter loss than with the total amount of precipitation. The relationship consisted of two lines. The slope of the first line, indicative of the sensitivity of the decomposition to varying numbers of rainfall events, correlated well with the watersoluble fraction (P<0.05), the C:N ratio (P<0.05), and the polyphenol: N ratio (P<0.01) of the residues. The decomposition process was shown to be dominated by microbial catabolism, rather than leaching. Because the decomposition of the higher quality residues is affected by varying rainfall patterns and because rainfall may often be unpredictable in frequency and intensity, synchronization of N released from a significant part of the decomposing residue with crop N demand may require additional management practices.

Plot Techniques for Assessment of Bunch Weight in Banana Trials under Two Systems of Crop Management

AbstractBanana (Musa spp.) is an important perennial crop in tropical countries. Testing improved germplasm and/or agronomic practices to increase productivity requires accuracy and precision. The objectives of this study were to determine the optimum plot size (i.e., number of plants per experimental plot) and the number of replications to detect significant true mean differences in bunch weight (i.e., commercial yield) between treatments. Three uniformity trials of the cultivar Valery grown in Ultisols under two different management practices (alley cropping of banana with multispecies hedgerows and monocropping of banana in cleared land) and at two locations in the humid forest zone of sub‐Saharan Africa were used. The methods of maximum curvature and comparison of variances were used to determine optimum plot size, while the number of replications was estimated by Hatheway's method. This statistical procedure considered an expected relative magnitude of differences between treatment means at a specific probability level and the relationship between the coefficient of variation and soil heterogeneity. The experimental plot should have a single row of 5 plants for banana in an alley cropping system, whereas single rows of 20 plants plot−1 are required in a monocropping system. This finding indicates that alley cropping of banana with multispecies hedgerows may be an adequate system not only to maintain diversity but also for greater efficiency in testing improved germplasm. A table was developed, indicating the expected detectable true mean differences for bunch weight per plant for different number of treatments tested (5–30), plants per plot (5–40), replications (2–6), and management practices. This table allows musa researchers to select minimum trial sizes, according to their objectives and available resources. For example, when 30 treatments are tested in alley cropping fields, using randomized complete block designs with two replications of 10 plants plot−1, a true bunch weight mean difference of 15% may be found to be significant.

Plant residue decomposition and nitrogen dynamics in an alley cropping and an annual legume‐based cropping system

Abstract Field experiments were conducted to compare plant residue decomposition and nitrogen (N) dynamics in an alley cropping system (AC) and an annual legume‐based cropping system (NA) in the Piedmont region of Georgia, USA. The hedgerows of the alley cropping system consisted of Albizia julibrissin (albizia) established in January 1990. Hedges were four meters apart with a spacing within rows of one‐half meter. A rotation beginning with Mucuna deeringiana (velvet bean) followed by a winter annual crop of Trifolium incarnatum L. (crimson clover), a summer crop of Sorghum bicolor (L.) Moench (grain sorghum) and a winter crop of Triticum aestivum L. (wheat) was established in the alley cropping system and a control annual cropping system. All crops were grown using no‐tillage systems. Plant residue decomposition and N dynamics were measured using litterbag technologies on crimson clover, albizia, and grain sorghum. Soil and plant total N, decay rate constants (k) for dry matter, soil potentially minerali...

Influence of pruning management on P and N distribution and use efficiency by N2 fixing and non-N2 fixing trees used in alley cropping systems

Pruning of hedgerow trees is an important management practice for the successful establishment of an alley cropping system. Although pruning affects biomass production, only meager evidence of this management on distribution of nutrients among the different plant organs after tree regrowth is available. This study examined the effect of pruning on the distribution and use efficiency of N and P in a N2 fixing leguminous tree species, Gliricidia sepium, and two non-N2 fixing leguminous tree species, Senna siamea and S. spectabilis, grown in a field on an Alfisol (low in P) at Fashola (Guinea Savanna Zone), Southwestern Nigeria. Four P rates, 0, 20, 40 and 80 kg P ha−1 as single superphosphate were used and management treatments included pruned versus unpruned plants. The 15N isotope dilution technique was used to measure N2 fixation in G. sepium. Partitioning of total P among different plant organs was influenced by plant species and pruning management, but was not affected by P application rates. The distribution of total P in the various plant organs followed that of dry matter yield while N partitioning had a different pattern. Pruned plants distributed about 118% more total P to branches and had a higher physiological P use efficiency (PPUE) than unpruned plants. Leaves were the biggest sink for total N and N allocation in the other plant organs was influenced by plant species and pruning management, G. sepium had relatively more of its total N and P partitioned into roots (about double that of the non-N2 fixing trees) but had a lower PPUE. Unpruned and pruned G. sepium derived 35 and 54% respectively of their total N from atmospheric N2, with about 54% of the fixed N2 being allocated to leaves and roots. Results showed that N and P pools turned over in the branches during plant regrowth after pruning but the causative factors associated with this phenomenon were not clear.

Decomposition ofCassia siamealoppings in semiarid Machakos, Kenya

The rate of decomposition of Cassia siamea Lam. prunings in an alley cropping system was investigated using litter bags in the semiarid area of the Machakos District, Kenya, during the short rains of 1988 and the long rains of 1989. Cassia siamea had been grown as the hedgerow species since 1983. Loppings were used as mulch incorporated into the soil for green manuring. Approximately 70–90% of the loppings could decompose exponentially within 60 days, a relatively low rate. Younger material decomposed faster in the long rains than older material in the short rains. Nitrogen content and C/N ratios explain this result. They also meet critical values in the literature for nitrogen availability to the crop. Position in the alleys had no significant influence on decomposition. Outside the rainy seasons, termite activity appreciably influenced diminution of decomposing material. Fungi had a role throughout, but bacteria may be supposed to be the predominant agent within the rainy seasons.

Economic analysis of cut-and-carry, and alley cropping systems of mulch production for plantains in south-eastern Nigeria

Organic mulch is beneficial to plantain because it maintains soil fertility, prevents erosion and suppresses weeds. Mulch availability is however a major constraint. Mulching in a cut-and-carry system withPennisetum purpureum Schum. (elephant grass) was compared with mulching with the prunings ofAlchornea cordifolia (Schum. & Thonn.),Dactyladenia barteri (Hook. f. ex Oliv.)Engel. (Syn.Acioa barteri),Gmelina arborea (Roxb.) andSenna siamea (Lam.) Irwin & Barneby (Syn.Cassia siamea) in alley cropping systems. Plantain inPennisetum mulch treatment gave the highest bunch yield, but similar net revenues per hectare as theDactyladenia treatment, whileGmelina, Alchornea andSenna treatments produced the lowest incomes. But when the land required to producePennisetum mulch was included in the economic analysis, the net revenue per hectare was negative over three years of cropping. The returns to labour were also much lower for thePennisetum compared to the alley cropping systems. Among the in-situ mulch sources,Gmelina had the highest labour requirement because of the high pruning frequency. In addition, weeding inGmelina, Alchornea andSenna treatments resulted in high labour demand due to the rapid decomposition of the mulch materials leaving the soil bare for weeds to invade.Dactyladenia alley cropping was the most profitable of the five plantain production systems studied.

Alley cropping and mulching withErythrina poeppigiana (Walp.) O. F. Cook andGliricidia sepium (Jacq.) Walp.: effects on maize/weed competition

The potential of allye cropping systems to sustain a high productivity with low external inputs and the reduction of maize/weed competition through weed suppression in different alley cropping and sole-cropped mulched systems was studied in Costa Rica at CATIE. Data were recorded eight years after establishment of the experiment. Plant residues ofErythrina poeppigiana trees (10 t/ha dry matter) planted at 6 by 3 m reduced weed biomass by 52%, whileGliricidia sepium trees (12 t/ha dry matter) planted at 6 by 0.5 m reduced weed biomass by 28%, in comparison to controls.Erythrina had a considerable impact on grass weeds, whileGliricidia reduced the incidence of some dicot weeds. Weed competition significantly reduced maize yield in all systems. Nevertheless weed suppression contributed to the higher maize grain yield underErythrina andGliricidia alley cropping of 3.8 t per hectare as opposed to the unmulched control yield of 2.0 t per hectare.

Estimating Dinitrogen Fixation of Hedgerow Vegetation Using the Nitrogen-15 Natural Abundance Method

Leguminous trees play a major role in alley farming or hedgerow by providing or recycling N and organic matter to annual crops. Little is known, however, about their capacity to fix N2 under field conditions because of methodological difficulties. This study evaluated whether the 15N natural abundance (δ15N) method could be applied successfully to an alley-cropping system to estimate N2 fixation by Gliricidia sepium (Jacq.) Walp. The study also assessed the suitability of the non-nodulating legume Cassia spectabilis (L.) DC [syn. Senna spectabilis (DC.) Irwin and Barneby] as a suitable reference for investigations with N2-fixing trees. The hedgerow species were planted in double rows, 3 m long with 5-m-wide alleyways, at an acid upland site in the Philippines. The δ15N of total N of Cassia and Gliricidia prunings was determined from six samplings between January 1990 (17 mo after establishment) and July 1991. The δ15N of the total N of samples from nonfixing Cassia ranged from 4.47 to 7.28‰ with an average and standard error of 6.16 ± 0.41‰. These values were similar to those of extractable N of soil from different soil depths, ranging from 4.66 to 7.33%, suggesting that Cassia is a suitable nonfixing reference species. The changes in δ15N of total N of prunings were similar in both tree species; therefore, the observed variation was considered not to have interferred with estimation of N2 fixation (%Ndfa). At four of the six sampling times, Gliricidia had an Ndfa close to 50%, whereas at other two sampling dates the Ndfa dropped to 30 and 35%. This study also provides the first quantitative data demonstrating that Cassia is a non-N2-fixing legume.

Radiation regime and nitrogen supply in modelled alley cropping systems ofErythrina poeppigiana with sequential maize-bean cultivation

A simulation study relating the effect of the spatial arrangement of trees on the photon exposure above an associated crop (PEi) was carried out for an alley cropping system of the leguminous treeErythrina poeppigiana (Walpers) O. F. Cook with sequential maize-bean cultivation. These results were combined with estimates of the nitrogen supplied by prunings from different tree densities to rank the arrangements. A significant difference was found in the PEi between the east-west and north-south-oriented alleys. The latter exhibited more areas of moderate shade, while the former has unshaded centres and heavily shaded parts next to the tree row. When the simulated PEi data was combined with the N supply from tree residues, the wider between-row tree spacings (6 or 8 m, with 1 or 2 m within-row spacing) appeared to be best. In general, to minimize shading of the crop, yet maintain a sufficient supply of organic matter and nitrogen in prunings, alley cropping tree arrangements of high between-row and low within-row spacings seem to be most promising. The east-west orientation seems to be more promising than north-south.

Nitrogen cycling in leucaena (Leucaena leucocephala) alley cropping in semi-arid tropics

In an alley cropping system, prunings from the hedgerow legume are expected to supply nitrogen (N) to the associated cereal. However, this may not be sufficient to achieve maximum crop yield. Three field experiments with alley-cropped maize were conducted in a semi-arid environment in northern Australia to determine: (1) the effect of N fertilizer on maize growth in the presence of fresh leucaena prunings; (2) the effect of incorporation of leucaena and maize residues on maize yield and the fate of plant residue 15 N in the alley cropping system; and (3) the 15 N recovery by maize from 15 N-labelled leucaena, maize residues and ammonium sulphate fertilizer []

Participative farmer testing of four low external input technologies, to address soil fertility decline in Mono province (Benin)

Farmer participation in experimenting with technologies in Mono province (Benin) increased when attention was focused on their major problems. One such problem is soil degradation caused by over-exploitation of land. Four different low external input technologies, all with leguminous components and half of them based on agroforestry, have been tested since 1990 by sub-groups of farmers, who all belong to a discussion group focussing on this problem. The technologies are: (i) a short season fallow of Mucuna pruriens var. utilis; (ii) an improved perennial tree fallow of Acacia auriculiformis; (iii) a short season fallow of pigeonpea; and (iv) an alley-cropping system on the basis of alternating hedgerows of Gliricidia sepium and Leucaena leucocephala. The first two technologies were aimed at the regeneration of very degraded plots, while the latter two technologies concentrate on stabilising still moderately fertile land. Some impressions and results are discussed.