While a good understanding exists of the effects of low-cost natural vegetative contour strips (NVS) in deep acidic soil environments, little is known about the benefits and constraints of using NVS under severely degraded calcerous soil condition. Calcerous soils cover about 20% of the total land area of the philippines, and are also wide-spread in other parts of Southeast asia. They therefore, characterize an important environment that millions of upland farmers depend upon for a living in the region. Shallow calcareous soils are particularly common in the Central Phillipines covering more than half of the total land area of the Visayan islands. Under shallow soil conditions, the effects of soil scouring can be severe because the entire soil may be removed down to the parent rock material.
Tag: alley cropping
Contour grass strips and tillage affect corn production on Philippine steepland oxisols
Cultivated steeplands in the humid tropics require better soil management systems to meet increasing food demands. The objective of this 4-yr study was to evaluate the following four contour soil management systems for corn (Zea mays L.) production: (i) contour moldboard plowing (CP); (ii) ridge tillage (RT); (iii) natural grass barrier strips plus moldboard plowing (GCP); and (iv) grass strips plus ridge tillage (GRT). Eight successive corn crops were grown in limed and fertilized soil from 1992 through 1995. On a total land area basis (cropped area plus the area occupied by the grass strips), the 1995 mean grain yields for RT (10.8 Mg ha1) and GRT (10.3 Mg ha1) were significantly greater than yields for CP (10.0 Mg ha1) and GCP (9.6 Mg ha1). The corn grain yields for the CP and RT systems before 1995 ranged from 1.3 Mg ha1 in 1992 to 8.4 Mg ha1 in 1993, while comparable GCP and GRT yields ranged from 1.4 to 7.6 Mg ha1 Excluding the area occupied by the grass strips, the GRT system had the highest 4-yr average corn yield (7.3 Mg ha1) followed by the GCP (7.2 Mg ha1), RT (6.9 Mg ha1) and CP (6.7 Mg ha1) systems. Yields improved during the 1994 and 1995 growing seasons when the grass was not permitted to grow as tall. The combination of contour ridge tillage and contour grass strips has potential for sustaining crop productivity on highly erodible steepland soils in the humid tropics.
Agronomic and economic appraisal of alley cropping with Leucaena diversifolia on an acid soil in the highlands of Burundi
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 ha1) 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.
A tree/crop interface design and its use for evaluating the potential of hedgerow intercropping
The paper describes a tree/crop interface (TCI) experiment designed to investigate the effects of row orientation using Leucaena leucocephala Lam. Each TCI plot consisted of a regularly pruned Leucaena hedge in the middle and 12 crop rows on either side. Eight such plots were arranged at 45° around a sole Leucaena plot with rows oriented in four compass directions viz., North-South, East-West, Northeast-Southwest and Northwest-Southeast. Results of four years from 1984 to 1987 did not show any effect of row orientation, and similarly, no effect was seen on crop rows due to their location on the windward or leeward side of the hedge. The TCI effect was positive on the first crop row in the first year because Leucaena grew slowly, but depressed the yield of the first 4 to 6 crop rows(1.8 to 2.7 m from hedge) in subsequent years. The negative effect of Leucaena was noted more on sunflower in a relatively dry year than on sorghum in other years. Results from the TCI plots were used to estimate the yield of five hedgerow intercropping (HI) systems with varying alley widths (2.7 to 9.9 m). Comparison with sole stands of Leucaena and crops indicated that HI was more productive particularly at close alley widths. For example, hedges spaced at 2.7 m and 3.6 m averaged 37% and 25% higher productivity than the respective sole stands; but this advantage may be an overestimation of the real potential. The relevance of TCI experiments for studying agroforestry systems, their merits and limitations, especially of the design employed in this study are discussed.
Rapid soil redistribution within alleys: why simple extension models for contour hedgerows may not be appropriate
Nutrient harvesting-the tree-root safety net
The hypothesis that deep rooting trees intercept nutrients which have leached below the crop rooting zone and compete for nutrients less strongly than trees rooting mainly within the crop root zone was tested in a mixed alley-cropping system on an Ultisol in North Lampung, Sumatra by measuring uptake of 15N placed at varying soildepths. Gliricidia sepillm, with its predominantly shallow root system, competed strongly for N with the crop and took up little 15N from lower soil depths. In contrast Peltophorum dasyrrachis roots exhibited a higher nutrient uptake activity at lower soildepth thus providing an active ‘safety-net’. Root activity as well as root length density has to be taken into account when assessing the efficiency of the safety-net.i’rellnlnary modelling results using WaNuLCAS suggested that Peltophonlln roots inthe 40-60 cm soil layer could reduce leaching by 5-10% over the course of a maize crop cycle in the rainy season.
Productivity of annual cropping and agroforestry systems on a shallow alfisol in semi-arid India
An experiment was conducted at ICRISAT Center, Patancheru, India from June 1984 to April 1988 on a shallow Alfisol to determine whether the productivity of annual crop systems can be improved by adding perennial species such as Leucaena leucocephala managed as hedgerows. Except in the first year, crop yields were suppressed by Leucaena due to competition for moisture. The severity of competition was high in years of low rainfall and on long-duration crops such as castor and pigeonpea. Based on total biomass, sole Leucaena was most productive; even on the basis of land productivity requiring both Leucaena fodder and annual crops, alley cropping had little or no advantage over block planting of both components. Application of hedge prunings as green manure or mulch on top of 60 kg N and 30 kg P2O5ha1 to annual crops did not show any benefit during the experimental period, characterized by below average rainfall. Indications are that (i) alley cropping was beneficial in terms of soil and water conservation with less runoff and soil loss with 3 m alleys than with 5.4 m alleys, and (ii) root pruning or deep ploughing might be effective in reducing moisture competition.
Innovations within upland rice-based systems in northern Vietnam with Tephrosia candida as fallow species, hedgerow, or mulch: net returns and farmers’ response
Land degradation and crop yield decreases in tropical uplands in general and in southeast Asia have been recognised as the main problems arising from intensification of upland cultivation. With the purpose to search for solutions to these problems, agroforestry systems with a leguminous shrub Tephrosia candida (Roxb.) D.C. were experimentally tested on-farm in an upland rice (Oryza sativa L.) system on sloping land in northern Vietnam during the period 1996–1999. The upland rice-based systems tested were: (1) fallow crop rotation, including natural fallow (NaFa) and Tephrosia fallow (TepFa); (2) continuous cropping, including monocropping (Mono), Tephrosia hedgerow intercropping (TepAl), and Tephrosia mulch transfer (TepMu). In this paper, findings concerning net returns per labour day and the response of farmers to the test systems are presented. The Tephrosia systems (TepFa, TepAl, and TepMu) and the existing systems (NaFa and Mono) were evaluated using both experimental measurements and participatory rural appraisal (PRA) techniques. In the different treatments over a 4-year rotation, 386–778 labour days ha1 were used, while 2612–4924 kg ha1 upland rice grain and 939–9601 kg ha1 fuel wood were harvested. The upland rice grain harvested was enough to feed 8.7–16.4 persons ha1. During the same period, the economic net present values were positive for the NaFa and TepMu treatments, but negative for the TepFa, Mono and TepAl treatments. The returns per unit labour were 3.7–6.7 kg rice or US$ 0.8–1.44 labour per day. Farmer criteria concerning management, labour input and soil conservation were well in accordance with the findings on labour input, crop yields and net returns. The Tephrosia systems seemed not to be rational alternatives for situations where the natural fallow systems are still viable. However, the Tephrosia fallow and the Tephrosia mulch transfer systems could increase crop yield per hectare at acceptable rates of return to labour.
Tree-crop Interactions for Below-ground Resources in Drylands: Root Structure and Function
An experiment was conducted at ICRISAT Center, Patancheru, India from June 1984 to April 1988 on a shallow Alfisol to determine whether the productivity of annual crop systems can be improved by adding perennial species such as Leucaena leucocephala managed as hedgerows. Except in the first year, crop yields were suppressed by Leucaena due to competition for moisture. The severity of competition was high in years of low rainfall and on long-duration crops such as castor and pigeonpea. Based on total biomass, sole Leucaena was most productive; even on the basis of land productivity requiring both Leucaena fodder and annual crops, alley cropping had little or no advantage over block planting of both components. Application of hedge prunings as green manure or mulch on top of 60 kg N and 30 kg P2O5ha1 to annual crops did not show any benefit during the experimental period, characterized by below average rainfall. Indications are that (i) alley cropping was beneficial in terms of soil and water conservation with less runoff and soil loss with 3 m alleys than with 5.4 m alleys, and (ii) root pruning or deep ploughing might be effective in reducing moisture competition.
Insect pests and beneficial arthropod populations under different hedgerow intercropping systems in semiarid Kenya
Exploiting the principles of biological control of crop pests is an important management strategy for the resource-poor smallholder farmers of the tropics. The effects of nine hedgerow species on the abundance of major insect pests of beans and maize, and predatory/parasitic-arthropods were monitored over two cropping seasons and the intervening dry period. The tree/shrub species evaluated were Gliricidia sepium, Grevillea robusta, Senna siamea, Senna spectabilis, Flemingea congesta, Croton megalocarpus, Morus alba, Calliandra calothyrsus and Lantana camara. Arthropod abundance was monitored through counts of infested plants and using yellow pan and pitfall traps. Beanfly (Ophiomyia spp.) infestation was significantly higher in the presence of hedgerows (35%) than in their absence (25%). Hedgerows did not influence aphid (Aphis fabae) infestation of beans. In contrast, maize associated with hedgerows experienced significantly lower stalk borer (Busseola fusca and Chilo spp.) and aphid (Rhophalosiphum maidis) infestations than pure maize, the margin of difference being 13% and 11% respectively for the two pests. Ladybird beetles closely followed their prey, aphids, with significantly higher catches in sole cropped-plots than in hedgerow-plots and away from hedgerows. Activity of wasps was significantly greater close to hedgerows than away from them. Spider catches during maize season were 77% greater in the presence of hedgerows than in their absence, but catches during other seasons were similar between the two cropping systems. Differences among hedgerow species were not significant for most of the arthropods monitored, except that beanfly infestation was greater with Gliricidia hedgerows. The study indicates that the effect of hedgerows on pest infestations of crops and their role as refugia for predators cannot be generalized but depends on the specific arthropods.