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Alley cropping − the intentional integration of trees and crops − is one of the most common agroforestry practices around the world. To better understand its potential to provide economic and ecological benefits over separately cultivated trees and crops, alley cropping research has expanded significantly over the last few decades. While alley cropping is inherently diverse in its composition and function, no comprehensive inventory of its many forms has been performed. We analyzed historical and geo-climatic trends in species composition and function of all alley cropping field experiments in the literature. A total of 1244 publications from 77 countries over the last 35 years were included. Tree diversity was high across all regions, with 410 species utilized from 192 genera. Dominant trees included Populus and Juglans in the temperate zone, Eucalyptus and Populus in the subtropics, and Leucaena and Gliricidia in the tropics. Alley crops were also highly diverse − 276 species within 181 genera − but were dominated by a few annual grains in each region. Despite the diversity in composition across systems, the agricultural functions of both trees and crops were limited. Trees for biomass were utilized in 82% of temperate experiments, while trees for food, fodder, and crop facilitation were more common in the subtropics and tropics. To best orient the growing interest in alley cropping around the world, this inventory was used to identify existing gaps in the literature and inform future opportunities in alley cropping research. Four frontiers in alley cropping research were identified as (1) within-system tree diversity, (2) tree crops for food and fodder production, (3) perennial alley crops, and (4) trees for crop facilitation via shade, nitrogen fixation, and mulch production.

In the temperate zone, alley cropping is promoted as a climate change-resilient agroforestry practice for the provision of biogenic energy carriers. However, little information is available on the potential of such cropping systems as feedstock for biofuel production. In a field trial in Central Europe, the triennial performance of alley cropping systems was assessed. The systems consisted of clover-grass, a native diversity-oriented grassland mixture and multi-rows of willows. They were compared to a willow and grassland control adjacent to the trial area. Three different conversion technologies were applied to grassland feedstock and analyzed for relevant quality parameters. Net energy balances were calculated to determine the potential of the cropping systems and the associated controls as providers of biogenic energy carriers. The grassland control had the highest triennial yield (18 t DM ha−1), whereas pure willow stands were less productive with 7 t DM ha−1. Alley cropping was intermediate with 12 t DM ha−1 on average. Net energy yield of the clover-grass based systems was highest in the grassland control for all conversion technologies, whereas values of the diversity-based systems in the control and the alley cropping system achieved similar values. This study only investigated the first 3 years after establishment, when growth rates of shrub willows were still low. Thus, more research is needed to evaluate the long-term performance of agroforestry systems with shrub willows and herbaceous crops.

Long-term effects of alley cropping on soils in the temperate zone are not widely known. Management, landscape, and soil depth effects on soil physical and biological properties were examined in a silver maple (Acer saccharinum L.) no-till corn (Zea mays L.)- soybean (Glycine max L.) rotation established in 1990 in northeast Missouri. Soils from crop alleys and tree rows were collected along transects traversing upper to lower landscape positions at three depths. Fluorescein diacetate hydrolase (FDA), β-glucosidase, β-glucosaminidase, and dehydrogenase activities were measured. Soil bulk density, aggregate stability, carbon (C), nitrogen N), and enzyme activities decreased with soil depth in alley and tree rows except for glucosaminidase. Soil physical and biological parameters did not differ significantly between alley and tree row. Landscape position effects were not significant for management or depth. Tree establishment improves soil quality in the crop alley as the system matures with improvements extended throughout the soil profile.

Alley cropping systems may influence soil water movement and the water budget because of its complex interactions between crop and tree rooting systems. The objective of this paper was to evaluate water balance and water competition in an alley cropping system, consisting of deciduous tree wild jujube (Choerospondias axillaris) and economic crop peanut (Arachis hypogaea) within subtropical China. Five treatments (20- by 6-m plots) with three replications were included in this study. The treatments were monoculture peanut cropping (P), monoculture younger trees (T1), monoculture older trees (T2), peanut intercropped with younger trees (T1P), and peanut intercropped with older trees (T2P). A multi-layered water balance model, with water movement between soil layers, was implemented by the measurement of soil water potential using sets of tensiometers during the periods from March 1999 to December 2002. The spatial and temporal variations of soil water regime indicated that the trees used soil water below the 60-cm soil depth and alleviated the water stress. The direction of soil water movement indicated that soil water moved to the tree row, which indicated that trees competed with peanuts for water, especially during the seasonal drought period. Water competition was related to the tree spacing and tree age. Compared to the tree monoculture systems, the alley cropping system significantly influenced water budget components and water use patterns, as indicated by the increased evapotranspiration (6–11%), and decreased net drainage (7–45%), water storage (6–29%), and runoff (50–60%). Furthermore, alley cropping systems encouraged the rapid growth of trees, and depressed the biomass and yield of peanuts by 20–50% associated with tree shading effects. The results suggest that competition for water and light must be taken into account when optimizing the alley cropping system.

Little information is available on soil respiration and microbial biomass in soils under agroforestry systems. We measured soil respiration rate and microbial biomass under two age classes (young and old) of a pecan (Carya illinoinensis) — cotton (Gossypium hirsutum) alley cropping system, two age classes of pecan orchards, and a cotton monoculture on a well-drained, Redbay sandy loam (a fine-loamy, siliceous, thermic Rhodic Paleudult) in southern USA. Soil respiration was quantified monthly during the growing season from May to November 2001 using the soda-lime technique and was corrected based on infrared gas analyzer (IRGA) measurements. The overall soil respiration rates ranged from 177 to 776 mg CO2 m−2 h−1. During the growing season, soil respiration was higher in the old alley cropping system than in the young alley cropping system, the old pecan orchard, the young pecan orchard, and the monoculture. Microbial biomass C was higher in the old alley cropping system (375 mg C kg−1) and in the old pecan orchard (376 mg C kg−1) compared to the young alley cropping system (118 mg C kg−1), young pecan orchard (88 mg C kg−1), and the cotton monoculture (163 mg C kg−1). Soil respiration was correlated positively with soil temperature, microbial biomass, organic matter, and fine root biomass. The effect of alley cropping on soil properties during the brief history of alley cropping was not significant except in the old systems, where there was a trend of increasing soil respiration with short-term alley cropping. Over time, different land use and management practices influenced soil properties such as soil temperature, moisture, microbial biomass, organic matter, and fine root biomass, which in turn affected the magnitude of soil respiration. Our results suggest that trees in agroforestry systems have the potential to enhance soil fertility and sustainability of farmlands by improving soil microbial activity and accreting residual soil carbon.

Soil bacterial and fungal dynamics were measured in an alley cropping system using direct microscopy techniques. The alley cropping system involved hedgerows of alder trees (Alnus rubra) and sweet corn (Zea mays) grown in the alleys. Trees were periodically coppiced and prunings were incorporated into the soil as green manure. Active fungal and bacterial biomass were greatest in tree rows and declined with distance from the trees. Active fungal biomass was greatest at the first year July sampling, ranging from 44 mg g dry soil ˇ1 in the tree row to 22 mg g dry soil ˇ1 in the middle of the alley. Bacterial biomass in all sampling locations peaked during May before coppicing of trees and cultivation of the alley. Bacterial and fungal biomass in the middle of the alley were similar to sweet corn monocropping plots throughout the growing season. The results suggested that the relatively low pruning biomass that can be produced and incorporated into the soil of temperate climate alley cropping systems compared to tropical alley cropping systems has little effect on microbial biomass. However, additional green manure in the form of leaf fall, additional below ground substrate from tree roots, and favorable conditions in untilled tree rows contribute to higher soil fungal and bacterial counts in and near the tree rows. # 1999 Elsevier Science B.V. All rights reserved.

The objective of this study was to determine crop and tree productivity in several alley cropping planting patterns. The four- year study was conducted in western Oregon, United States and involved irrigated sweet corn (Zea mays) intercropped between hedgerows of red alder (Alnus rubra) and black locust (Robina pseudoacacia). Three alley cropping planting patterns with variable plant populations and tree-crop proximity were tested with each tree species in a randomized block design. Space available to trees and crops determined yield of both plant components. High crop yield coincided with low pruning yield, and vice versa. Compared to monocropping, yield reductions in traditional alley cropping planting patterns with widely spaced, double tree rows ranged from 5% to 15%. A. rubra and R. pseudoacacia coppiced readily and produced 0.9 to 4.7 tons of dry matter pruning biomass per growing season, depending on planting pattern and year. A. rubra yield continually increased during the trial, while the ability of R. pseudoacacia to produce green manure after frequent coppicing appeared to weaken. After four years, soil organic matter was 4 to 7% higher in the topsoil of an alley cropping system compared to a monocropping system. However, continuous growing of sweet corn resulted in decreased soil organic matter levels in both cropping systems compared to original levels. Crop yield reductions and the need for additional management inputs constrain the implementation of alley cropping in temperate climates. Only if benefits other than minor soil fertility improvements are realized is alley cropping a feasible alternative in temperate climate regions.

A longterm alley cropping trial was undertaken on an eroded Oxic paleustalf in the forest-savanna transition zone of southwestern Nigeria from 1981–1993. Two nitrogen fixing hedgerow species (Gliricidia sepium and Leucaena leucocephala) and two non legume hedgerow species (Alchornea cordifolia and Dactyladenia barteri) were used in the trial compared to a control (with no hedgerow) treatment. Plots were sequentially cropped with maize (main season) followed by cowpea (minor season). With 4 m interhedgerow spacing and pruning at 0.75 m height, the mean annual pruning biomass yields were observed in the following order: Leucaena (7.1 t ha-1 ) > Gliricidia (4.9 t ha-1 ) > Alchornea (3.7 t ha-1) > Dactyladenia (3.0 t ha-1 ). Alley cropping with the four woody species greatly enhanced the total plot (woody species + crop) biomass yield/ha as follows; Leucaena (21.8 t ha-1) > Gliricidia (17.7 t ha-1) > Alchornea (11.7 t ha-1) > Dactyladenia (9.5 t ha-1). Total biomass yield of crops in control plot was 5.3 t ha-1. Higher biomass yields with alley cropping also increased nutrient yield and cycling. Gliricidia and Leucaena showed higher nutrient yields than Alchornea and Dactyladenia. Alley cropping with Gliricidia and Leucaena could sustain maize yield at moderate level (>2 t ha-1), which would require a N-rate of 45 kg N ha-1 with sole cropping. Application of N in Gliricidia and Leucaena alley cropping still improved maize yield. Higher nitrogen rates are required for alley cropping with Alchornea and Dactyladenia hedgerows. A low rate of phosphorus application is needed for sustaining crop yields with all treatments. Occasional tillage is recommended to increase maize yield. Alley cropping and tillage showed little effect on cowpea seed yield. Surface soil properties declined with time with continuous cultivation. Alley cropping with woody species maintained higher soil organic carbon, phosphorus and potassium levels. Plots alley cropped with Gliricidia and Leucaena showed lower pH and extractable calcium level. Leucaena alley cropped plot also showed lower magnesium level. The decline in soil pH and extractable cations may be due to increased cation leaching with application of high rates of Gliricidia and Leucaena prunings. Alley cropping with the four woody species showed no effect on population of parasitic nematodes.

A field experiment was conducted for two years (1989– 1991) on a Vertisol in Bijapur, India in a split-plot design, replicated four times, to evaluate the potential of alley cropping post-rainy season sorghum between Leucaena hedgerows. Leucaena produced on average 2.74 t per ha of prunings and 1.57 t per ha of wood annually. Alley cropping decreased sorghum yields by 28 to 45% when all Leucaena prunings were removed from the system and by 21 to 24%, when on average 1.92 t per ha prunings were applied to the soil annually. The reduction of sorghum yield increased as higher rates of N were applied to sorghum. Although alley cropping increased organic carbon by 21% and available N by 19% at the time of crop sowing, it did not result in increased crop yields because of competition for water between hedgerows and crops. Calculation of land equivalent ratios based on total Leucaena biomass indicated that alley cropping was more productive than sole cropping of sorghum only in one year, and that, too, when no N was applied to sorghum. Therefore, alley cropping of Vertisols with post-rainy season sorghum is not likely to have any advantage in the short term.

Alley cropping would be acceptable to farmers in West Africa, if the amount of tree-crop competition could be reduced and crop yields increased and stabilized. The importance of overall tree-crop competition in alley cropping was therefore quantified at three locations in the Republic of Benin, by comparing the performance of a maize-cassava intercrop and mixed hedges of Gliricidia sepium and Flemingia macrophylla in an alley cropping system, where the tree-crop interaction was high, and in a cut and carry system with block plantings, where the interface was restricted to one face. The establishment and productivity of trees in both agroforestry systems depended strongly on the natural soil fertility of the site, K and Ca being critical for both species. Alley hedges produced progressively more cut dry matter with higher leaf proportions than tree blocks and hence yielded significantly higher nutrient masses. Overall, the cut dry matter from five cuttings per cropping season ranged among locations from 855 to 1651 kg ha−1 yr−1 for alley hedges and from 777 to 869 kg ha−1 yr−1 for tree blocks. Differences in yields of maize and cassava between both systems were insignificant in all three environments and all cropping years under observation. The results of this study suggest that the overall effect of tree-crop competition was unimportant, but that tree-tree competition was the decisive factor in determining the total system productivity.

Although alley cropping has been shown elsewhere to permit continuous cropping, it has not been widely tested in the highlands of east and central Africa where it has the additional potential of controlling soil erosion. The effect of four rates (0, 30, 60 and 90 kg N ha−1) of inorganic N on the performance of alley cropping using Leucaena diversifolia as the hedgerow species was studied in the central highlands of Burundi. Significant increase in maize yield (average of 26%) due to alley cropping was only first realised in 1992, three years after the commencement of the trial. In 1993, the average yield advantage of the alley cropping plots was 21%. The prunings augmented the response of maize yield to inorganic N in 1992 and 1993. Compared with the control, economic benefits over the five-year period for all the treatments were negative.

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...

Agroforestry has a high potential to sustain agricultural production in the humid tropics. One specific type of agroforestry, alley cropping, has received much attention as a means of producing staple food crops within an agroforestry system. There is now substantial evidence that alley cropping maintains soil fertility above levels found in pure annual cropping systems. Nevertheless, competition between the trees and crops can significantly reduce yields by the crop. A model is presented of how the balance between the improved soil fertility in alley cropping and competition from the trees determines the final crop performance. Better understanding of the factors that determine crop yield will enable improved design and management of alley cropping systems, and may allow alley cropping to become a more reliable means of improving crop production.

There is a need to develop viable farming systems for tropical uplands dominated by low-activity clay soils; such systems should ensure sustained crop production while protecting the soil resource base. Alley cropping has the potential to meet this need. For over a decade, the alley cropping technique has been tested, with varying results, in various agroecological zones. Results obtained thus far show that the best potential is on the high base-status soil in the humid and subhumid zones, and that crop production can be sustained in this ecozone with low chemical inputs. Further research is needed for other ecozones, particularly with inclusion of better adapted or indigenous hedgerow species. The potential and limitations of the alley cropping technique are highlighted and areas of future research discussed.

Poverty alleviation and environmental preservation are very important issues to many governments. Alley farming is beneficial to the environment because it conserves soil and sustains yields over time. Specifically, alley farming reduces soil erosion, which is a major problem in Thailand. Alley farming was conducted on a farmer’s field at Khaokwan Thong, a village in Uthaithani Province, Northern Thailand. We did a two-by-two factorial with and without alley farming, and with and without fertilizer. From this study, we observed that the two species used, Leucaena leucocephala and Acacia auriculiformis , grow well in Thailand, and that alley farming is suitable for Thailand. Few Thai farmers have heard about alley farming. However, it is nevertheless useful to know that there is potential for alley farming in Thailand using the two species. These plants, based upon the diameter and height measurements provided, grew well. Keywords: alley farming; poverty alleviation; environmental preservation; permanent field cultivation; sustainable agricultural technologies

Phosphorus availability was measured in soils under five cropping systems: alley cropping with Erythrina poeppigiana, alley cropping with Gliricidia sepium, sole cropping with Erythrina poeppigiana mulch applied, sole cropping with Gliricidia sepium mulch applied, sole cropping with no mulch. The following parameters were measured: 1) plant-available soil P assessed by P uptake of maize and bean bioassay plants; 2) phosphate desorbable by anion exchange resin; 3) adsorption of added P into isotopically exchangeable and non-exchangeable pools.

Most upland soils in humid and sub-humid tropical Africa are characterized by low inherent fertility and are also susceptible to soil erosion and compaction with cultivation. Based on simulation model, this study uses a capital budgeting approach to determine the profitability of alternative land use systems, taking into account the short and long-run impact of soil erosion on agricultural productivity in southwestern Nigeria. The fallow systems include: (1) two continuous cultivation alley cropping systems with leucaena hedgerows planted at 2 m and 4 m interhedgerows spacings: (2) the continuous cultivation no-till farming system; and (3) two traditional bush fallow systems with a 3-year cropping period in 6- and 12-year cycles. Under a 10 percent discount rate, when no yield penalties are imposed (reflecting the case of population density), the 12-year cycle shifting cultivation system is most profitable, followed by the 4 m alley cropping, the no-till, the 2 m alley cropping and the 6-year cycle shifting cultivation systems. When penalties are imposed on yields due to land being taken out of production because of fallow vegetation (reflecting the case of rising land values), the 4 m alley cropping is most profitable, followed by the no-till, the 2 m alley cropping, the 12- and 6-year cycle bush fallow systems. Thus where access to new forest land is ‘costless’, slight yield from erosion will not detract significantly from the immediate profit advantage of traditional bush fallow systems, with longer fallow periods.

The challenge facing research on increasing food production in tropical Africa is to develop low input systems that are not only sustainable but also economically viable. At the International Institute of Tropical Agriculture, substantial resources are devoted to research on alley cropping and live-mulch systems. These are among the potential alternatives to the bush fallow system that would sustain food production with low purchased inputs in the humid and subhumid tropics.

Red alder (Alnus rubra Bong) and black locust (Robina pseudoacacia L.) were intercropped in different planting patterns with sweet corn (Zea mays L.) in Corvallis, Oregon. In both years, sweet corn yield in alley cropping systems was significantly reduced when trees occupied more than 20 % of the total area. In the first year, higher yield were harvested in corn rows adjacent to the trees which compensated for reduced cropping area in the alley cropping systems. Low sweet corn yield coincided with high pruning biomass production. Red alder pruning biomass was small in the first year but equivalent to black locust in the following year. In the second year, soil microbial counts at planting time showed that bacterial and fungal activity in the tree rows was significantly higher compared to corn rows. At corn harvest, fungal activity was higher in tree rows and in corn rows adjacent to trees compared to corn rows more distant to the trees or corn rows in monocropping systems. It might be that higher sweet corn yield in rows next to the trees not only are the result of an increase in the amount of intercepted light but that below ground effects such as nitrogen mineralization from increased microbial activity or nitrogen transfer from the trees to the crop play an important role.

Alley cropping is a crop production system whereby food crops are planted in spaces created by hedgerows of selected leguminous shrubs. The leguminous shrubs supply nitrogen, organic materials and recycle leached nutrients. This study was elaborated to evaluate the effects of prunings of three leguminous shrubs on some soil properties in an alley cropping system. Soil chemical properties were improved in alley cropped sites. Soils under Cassia had the highest content of N,P,K and organic carbon with values of 0.344%, 45.6 ppm, 0.55 meq/100g and 2.32%, respectively, after the second maize crop. Bulk density, mean aggregate diameters and water holding capacity were better in the alley cropped sites, relative to control. Gravimetric moisture content was generally higher in the alley cropped sites and highest under Cassia. Cassia maintained a relatively high soil biomass C, probably because of its slow rate of decomposition. N fertilizer applied at 90 kg ha −1 promoted soil biomass C, essentially through increased shrub and maize dry matter production.

Alley cropping is an aspect of agroforestry being developed for small farmers in the tropics. It consists of establishing fast-growing leguminous shrubs or tree species in rows, then controlling the shading from the trees during cropping by pruning the branches which can be used as mulch or green manure to benefit the companion crops planted between the alleys. This paper attempts to assess the economic implications on labour utilization for the management of the leucaena hedgerows, on crop yields and the overall benefits from alley cropping with leucaena. The results show that although the management of leucaena trees increases labour requirements by about 50%, the system can sustain and increase maize yields by over 60%, reduce the use of nitrogenous fertilizers and give an attractive net income and marginal rate of return per unit cost. It gave a reasonable benefit-cost ratio of 1·23 to 1·32 and looks promising, especially for maize production in tropical areas.

In the Palcazu Valley alluvial Inceptisols are relay-cropped with maize-cassavaplantain in rotation with 2–5 years of tree fallow. These lands, of limited extent, yet important for Yanesha Indian subsistence production, are being cropped even more intensively as population increases and land is converted to other uses. The relay-planting of the tree-thicket combination Inga edulis with Desmodium ovalifolium into the on-farm crop sequence was evaluated as a means to accelerate fallow recovery and thereby shorten fallow rotations. Three experiments with Inga/Desmodium planted with cassava-plantain and one with rice under different weeding regimes after a Desmodium fallow were conducted. Inga and Desmodium were not chopped back or pruned during these experiments. Desmodium/Inga suppressed herbaceous weeds from one year after planting. Desmodium/Inga accumulated more woody biomass than natural fallows. Cassava yields were unaffected by the presence of Desmodium/Inga, while plantain yields were greater under Desmodium/Inga compared to natural weeds. Desmodium/Inga, while promising for shortening fallow rotations, demonstrated potential difficulties: increased labor for establishment, tendency of Desmodium to weediness in later crop cycles, and suppression of the natural regeneration of trees and shrubs.