Hedgerow Species Research Articles

Alley cropping: past achievements and future directions

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.

Spatial Variability in Soil Chemical Properties under Dactyladenia barteri, Alchornea cordifolia, Senna siamea and Gmelina arborea Hedgerows on an Acid Ultisol

SUMMARYSpatial nutrient distribution was studied under a three-and-a-half-year-old fallow of Dactyladenia barteri, Alchornea cordifolia, Senna siamea and Gmelina arborea hedgerows grown on an acid Ultisol in southeastern Nigeria. The objectives were to evaluate the nutrient cycling capacity and suitability of the hedgerow species for alley cropping. No consistent patterns were observed in the lateral distribution of soil pH, total nitrogen, organic carbon, available phosphorus, exchangeable cations (potassium, calcium, magnesium and sodium), total acidity and effective cation exchange capacity in the 4 m wide alleys formed between the hedgerow species. Senna siamea and Gmelina arborea tended to increase soil organic carbon, calcium, magnesium and effective cation exchange capacity, particularly in the top 50 cm, compared with Alchornea cordifolia and Dactyladenia barteri, and can therefore be recommended for soil fertility regeneration on acid Ultisols during periods of fallow. However, they appear to be less suitable for alley cropping than Dactyladenia barteri because they are shallow rooting.Propiedades químicas delo suelo bajo cuatro especies de seto vivo

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.

Crop-tree interactions in alley cropping systems on alluvial soils of the Upper Amazon Basin

A crop/hedgerow interface design was used to test three leguminous species,Inga edulis, Leucaena leucocephala andErythrina sp., for their potential use for alley cropping on alluvial soils in the upper Amazon Basin. Prunings were applied as mulch at three rates 0, 3.3 and 6.7 Mg dry matter/ha/crop. Competition, crop yields, nutrient budgets, and weed control were monitored for three consecutive crops of upland rice. Crop yield reductions were evident up to 1.5 m from each of the hedgerow species, but were more pronounced withLeucaena hedgerows. Additional mulch was able to compensate for these reduced yields close to the hedges inLeucaena leucocephala andErythrina but not inInga edulis systems. In general rice yields were higher withLeucaena leucocephala andErythrina mulch as compared toInga mulch, perhaps because of higher levels of available N provided by the rapidly decomposing leaves ofLeucaena leucocephala andErythrina sp. as compared toInga. Weed control was greater, however, with the slowly decomposingInga mulch. For all three hedgerow/crop systems there was a net export of P from the system which was exhibited by declining soil P levels and decreasing crop yields.

Increasing Gliricidia sepium and Cassia spectabilis biomass production

This paper examines the impact of spacing on biomass production of monocropped and mixed hedgerows of seedlings and cutting of Gliricidia sepium and Cassia spectabilis. The impact of lime on G. sepium biomass production was also evaluated. Seedlings survived better than cuttings; and no differences were observed between seedlings in either pattern at the highest density tested. Although spacing reduced inter-and intra-specific competition, total biomass production was greatest at higher densities. Mixing hedgerow species reduced intraspecific competition within C. spectabilis, resulting in increased biomass production. Six, 8 and 12 tons of lime per hectare significantly increased fresh G. sepium biomass production at all harvest dates except the first. Extrapolated to an alley cropping system, applying 6 t/ha of lime increased fresh cumulative G. sepium biomass production by almost 39 t/ha over the no lime treatment representing more than 200 kg N/ha.

Effects of Gliricidia sepium (Jacq.) Steud and Leucaena leucocephala (Lam.) de Wit on growth and development of Imperata cylindrica (L.) Raeuschel.

Field studies carried out in a forest transition site on a tropical Alfisol in southwestern Nigeria, show that shading by gliricidia (Gliricidia sepium (Jacq.) Steud) and leucaena (Leucaena leucocephala (Lam.) de Wit) hedgerow species reduced density of speargrass (Imperata cylindrica (L.) Raeuschel) by 67% and 51%, respectively. Shoot biomass of speargrass decreased by 81% and 78% in gliricidia and leucaena hedgerows, respectively. Reduction in speargrass rhizome biomass in gliricidia plots was 96% while rhizome reduction in the leucaena plots was nearly 90%. Rhizome mortality was significantly higher in gliricidia plots than in leucaena and control plots. The bulk of rhizomes was found between 10 cm and 20 cm of soil depth but rhizome did not penetrate further than 30 cm depth in the Alfisol in which this study was carried out. Gliricidia was better than leucaena hedgerow species in suppressing speargrass.

Effect of hedgerow species in alley cropping systems on surface soil physical properties of an Oxic Paleustalf in south-western Nigeria

SUMMARYEffects of hedgerow species on surface soil physical properties were studied in an on-going trial established since 1981 on an Oxic Paleustalf in southwestern Nigeria. The experimental treatments wereLeucaena leucocephala, Gliricidia sepium, Alchornea cordifoliaandAcioa barteriihedgerows planted at 4 m interhedgerow spacings and a control (no hedgerows). Plots were sequentia-ly cropped with maize (Zea mays) and cowpea (Vigna unguiculata). Soil physical properties, i.e. particle size distribution, bulk density, apparent pore size distribution and water infiltration, were monitored during the dry season in January and the main growing season in June 1989. Soil temperature was monitored at approximately monthly intervals from February to June 1989. Soil properties of alleycropped plots were superior to those of the control. Soil compaction was highest in the control and lowest withL. leucocephala. Between the hedgerow species, within-season increases in soil compaction were largest withA. cordifolia. Lowest soil temperatures were observed withL. leucocephalaandA. barterii. Frequency, quantity and quality of prunings produced by the hedgerow species appeared to have a major beneficial effect on soil physical properties.

The effects of severe hedge cutting on a breeding bird population

The effects on the bird population of a drastic cutback of all the internal hedges on a farm in central England were studied using the Common Birds Census mapping method. Numbers of hedgerow bird species were reduced after the cutback and it was birds along the affected hedges that were lost. Their numbers subsequently showed a full or partial recovery. In the year after the cutback birds of 5 of the most widespread and abundant hedgerow species on British farms temporarily packed some extra territories into unaffected hedges around the edge of the farm. The implications of the increased packing on the carrying capacity of farmland are briefly discussed.

Carbon relations and competition between woody species in a Central European hedgerow : III. Carbon and water balance on the leaf level.

Annual carbon and water balances of sun leaves were measured in the field for five competing woody hedgerow species of different successional stages. They were compared with carbon and water budgets of climax species from the literature. Climatic limitation of primary production, the effectiveness of leaf photosynthetic capacity in relation to actual carbon gain, costs and time of leaf formation and amortization, and net dry matter gain from the leaf were determined. Their relevance for a species' position during a natural succession from pioneer-invaded fallow land to a climax beech forest in Central Europe is discussed.

Hedgerows and hedgerow networks in landscape ecology

Hedgerows originated and coexist with agriculture. Their internal structure and species diversity vary widely with origin (planted, spontaneous, or remnant), farming practices in adjacent fields, and the refined art of hedgerow management. Most hedgerow species are forest-edge species, and apparently none is limited to hedgerows. Wide hedgerows composed of trees and shrubs appear to function as corridors for movement of many plants and animals across a landscape. The reduction of crop loss, by dampening pest population fluctuations with hedgerow predators, remains a hypothesis for study.

The Distribution and Abundance of the Spindle Tree, Euonymus europaeus, in Southern England with Particular Reference to Forecasting Infestations of the Black Bean Aphid, Aphis fabae

SUMMARY (1) A method is discussed for determining distribution and abundance of the spindle tree, Euonymus europaeus L. This could be used for other hedgerow species. (2) The work forms part of a study on forecasting of crop infestations of the black bean aphid, Aphisfabae Scop. based on overwintering populations on spindle for which corrections need to be made for the varying abundance of this winter host. (3) In southern England, spindle occurs in hedgerows, scrubland and woodland and is generally associated with calcareous soils where it is sometimes 'Common' (126-625 bushes/10 kM2) or locally 'Abundant' (>625/10 kM2) except on open downland where hedgerows are scarce or where the chalk and limestone are overlain by acidic soils. Elsewhere spindle is widely distributed, often at densities of about 6-25 bushes/10 km2 though it is 'Absent' or 'Very Rare' (<5 bushes/10 kM2) in some large areas such as the Fenland and much of the Midlands. It is, however, 'Occasional' to 'Common' (26-625 bushes/10 kM2) in some non-calcareous areas notably over parts of the Old Red Sandstone in Herefordshire and S. Shropshire and over Weald Clay. (4) The data were used to make adjustments to forecasts in sixteen areas in southern England. This notably improved forecasts in areas of high spindle density in contrast to areas of low density. The correction factors will therefore be applied only in high density areas.