In recent years, many studies have demonstrated the heterogeneity of the smallholder production environment. Yet agronomic research for development (R4D) that aims to identify and test options for increasing productivity has not consistently adapted its approaches to such heterogeneous conditions. This paper describes the challenges facing research, highlighting the importance of variation in evaluating the performance of soil management recommendations, integrating aspects of production risk management within the formulation of recommendations, and proposing alternative approaches to implement agronomic R4D. Approaches are illustrated using two multi-locational on-farm paired trials, each having one no-input control treatment and a treatment with fertilizer application for maize in Western Kenya and for beans in Eastern Rwanda. The diversity of treatment responses should be embraced rather than avoided to gain a better understanding of current context and its relation with past management.
Tag: sloping land
Networked and embedded scientific experiments will improve restoration outcomes
Vast areas of degraded land have proliferated worldwide. In response to this transformation, ambitious targets have been set to restore degraded ecosystems, such as the the Bonn Challenge, which aims to restore 350 million ha of forestland by 2030. Achieving such goals will require a larger evidence base of restoration studies, which could be realized by systematically embedding scientific experiments within restoration programs. We examine the feasibility of this strategy with examples of successful transdisciplinary research involving embedded experiments in associated fields, and recommend that such field sites be linked to create a global network of embedded experiments. To unify a networked approach, we call on restoration stakeholders to develop acceptable industry standards of experimental design. Finally, we suggest how to use this strategy effectively to meet the biome‐scale challenges of the coming decades.
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.
The effectiveness of contour hedgerows for soil and water conservation
Agroforestry Guide for Sloping Lands in Northwest Viet Nam (in Vietnamese Language)
Agroforestry Guide aims to provide users with basic knowledge on agroforestry as an agriculture, and natural resource management strategy. Intended for farmers and local extension workers, the Guide is written in a simple manner and presents basic steps in establishing agroforestry
Grain crop response to contour hedgerow systems on sloping Oxisols
Farming systems that minimize the rate of soil degradation and optimize food crop yields are needed to sustain soil productivity on sloping, acid, infertile soils in the humid tropics. Research was conducted on two Oxisols with slopes ranging from 22 to 30% to evaluate the performance of several contour hedgerow systems, with and without the addition of 60 kg N ha1 per crop, on rice (Oryza sativa) and maize (Zea mays L.) production. Contour hedgerows were double rows of the tree legume Gliricidia sepium (G); Gliricidia and the native grass Paspalum conjugatum (GPas); Gliricidia and an exotic fodder grass Penisetum purpureum (GPen); double rows of Penisetum (Pen); and a conventional open field (C) farming system without hedgerows. Gliricidia prunings and all crop residues were applied to the soil surface in the alleys, but Penisetum was harvested. Food crop yields in all hedgerow treatments tended to be less than the Control for the first two years, presumably due to the displacement of land planted to the food crop. In the third and the fourth years, the rice and maize yields of Treatments G and GPas exceeded the Control, most consistently when N was not applied. Penisetum reduced food crop yields regardless of N application presumably due to nutrient removal in the fodder. The results indicate that Gliricidia in a contour hedgerow increases food crop yield on strongly acid Oxisols by recycling nutrients and partially supplementing the N demand by the food crops
Soil and water conservation by contour hedging in the humid tropics of Peru
A study was conducted for over 6 years (October 1987–December 1993) in the humid tropics of Peru at Yurimaguas (annual rainfall 2200 mm) on a sloping (15–20%) Typic Paleudult to evaluate the soil and water conservation potential of contour hedgerows of Inga edulis (locally known as guaba). The experiment involved two treatments: (a) sole crops of rice and cowpea in annual rotation and (b) intercropping of annual crops between inga contour hedgerows 4 m apart, replicated three times in a randomised block design. Non-replicated plots of bare-fallow and secondary forest were also monitored for soil loss and runoff. Contour hedgerow intercropping conserved, on average annually, 287 mm water and 73 t ha1 soil, which represented 83% and 93% respectively of the amounts that were lost from sole cropping; it maintained soil nutrients at a much higher level and improved soil physical conditions compared with sole cropping of annuals. The significant soil and water conservation achieved by hedgerows, however, did not translate into a striking crop yield increase during the 5 year monitoring period; only the yields of three out of 15 crops in the last 2 years were significantly higher in hedgerow intercropping than in sole cropping. The lack of response was partly due to the fact that 22% of the land area was lost to the hedgerows and partly that a longer time span may be required to realise the benefits of soil conservation. However, contour hedgerow intercropping is recommended for moderate sloping lands of the humid tropics in Peru, considering the long-term conservation of land resource and the potential for continuous cropping with minimal inputs.
Appropriate spacing for natural vegetative filter strips in upland conservation farming systems
Natural vegetative filter strips (NVS) are attractive contour hedgerow system because they are simple to establish and maintain, control erosion effectively, and compete less with associated annual crops than other alternatives. The recommended practice has been to space the hedgerows every 1 meter drop in elevation. This results in close hedgerow spacing(3-6m apart) which removes considerable area from crop production. A collaborative study between the International Centre for Research in Agroforestry (ICRAF) and Misamis Orientak State College of Agriculture and Technology (MOSCAT) to determine the effect of NVS density om crop production and soil loss.