Optimizing resource distribution and crop productivity in hedgerow intercropping by manipulating tree arrangement

Abstract

The potential of tree arrangement in optimizing radiation and soil water distribution and crop yield of hedgerow intercropping systems was investigated using a Jatropha curcas-Pennisetum clandestinum (kikuyu) system (Ukulinga, South Africa). Treatments (1110 t ha −1 ) of Jatropha-only (JO), single-row Jatropha and kikuyu (SR), and double-row Jatropha and kikuyu (DR) were used. Treatments had asymmetrical radiation distribution across tree-crop (T-C) interfaces and different radiation interception by trees (JO: 27 %, SR: 11 %, DR: 8 %). Soil water varied among treatments and was asymmetrically distributed showing no consistent trend towards trees. Evapotranspiration was higher (p < 0.05) in SR than DR (13-65 %) and JO (16-37 %) for most part of the season. Estimated fine tree roots distribution was symmetrical in DR but not JO and SR. Total roots in SR were concentrated in the top 0.2 m (91 %) and beneath tree row (30 %), and varied inconsistently with distance from trees. Grass yields increased farther from tree rows and were higher in SR (8. ) also increased with distance from trees but irradiance correlated with grass yields poorly (R 2 < 0.32) despite high rainfall and no nutrient limitation. Considering total productivity and evapotranspiration, DR was better tree arrangement than SR. Water availability dictated T-C interactions and intercrop yield more than radiation. It was possible to optimize radiation and water distribution and intercrop growth by manipulating tree arrangement without changing density. KeywordsEfficient agroforestry design Growth Radiation use efficiency Silvopasture Tree-crop interactions INTRODUCTIONProduction of food crops and pastures in South Africa faces deterioration and limited arability of land and relatively low and erratic rainfall. Moreover, yields and food security are compromised by low agricultural production technologies practices and low inputs in resource-poor communities. One of such regions is the Coast Hinterland Thornveld region, which is classified as Bioresource Group 17 (Camp, 1997). This warm temperate region with annual rainfall (according to the Köppen classification) has an area of 113 367 ha and is characterized by severely degraded natural resources due to continuous burning to enhance fresh growth and selective overgrazing, poor water supply, frequent droughts and only 33% arable land. Vegetation in the area is wooded grasslands, woodlands and bushed grasslands dominated by secondary Acacia species and Aristida junciformis grass, which is an inedible by livestock (Everson et al. 2012). The potential exists for agroforestry to 1 be implemented a resource-efficient production system to rehabilitate the land, produce fodder to reduce pressure on the natural grasslands, and generate additional income by employing species that are tolerant to poor soils and not excessive water users.To ascertain sustainability of agroforestry systems, understanding factors and interactions involved is essential (Berlyn and Cho 2000;Ong et al 2000). Tree-crop (T-C) inte...

Agroforestry: An Appropriate and Sustainable Response to a Changing Climate in Southern Africa?

“…In higher latitudes, light limitation and growth reduction become more pronounced in the near tree vicinity of AFS and there may be a tendency for crops to present a reduced yield when shaded [25,63]. Ghezehei et al [64] studied the impact of hedgerow intercropping systems using a Jatropha curcas (L.)-Pennisetum clandestinum (Hochst. ex Chiov) system yield in KwaZulu-Natal, South Africa.…”

Yield and qualitative traits of sugarcane cultivated in agroforestry systems: Toward sustainable production systems

“…To determine the sustainability of an agroforestry system, an understanding of environmental factors and plant interactions is essential (Berlyn and Cho, 2000; Ong et al, 2000). Tree–crop interactions can be regulated effectively and interspecies competition can be minimized by employing efficient tree arrangements (Ghezehei et al, 2016) and by selecting compatible species (Bayala and Wallace, 2015; Ong and Kho, 2015).…”