A strategy for tree-perennial crop productivity: nursery phase nutrient additions in cocoa-shade agroforestry systems

Abstract

Shade tolerant species response to nutrient additions and light regulation by canopy trees in perennial agroforestry systems has been well documented. However, accelerated early growth, particularly in cocoa-shade systems, may be offset by competition for limited resources on nutrient poor sites. To date, few agroforestry management strategies focus on nutrient manipulation of the shade tree component or strategies for precision nutrient application. Our research objective was to diagnose interactions between nutrient supplied shade trees intercropped with cocoa. We established greenhouse trials in Kwadaso, Ghana cultivating Terminalia superba seedlings with four fertility treatment levels: conventional rate (current practices) under linear additions, and half, full and double conventional rate under exponential additions (steady-state nutrition) to determine maximal growth and nutrient uptake. After 4 months of additions in the nursery, pre-fertilized T. superba seedlings were then out-planted into field trials with cocoa seedlings. After 4 months of intercropping, cocoa associated with half rate exponentially supplied T. superba had significantly larger leaf area, greater leaf number, and higher nutrition (N and P uptake) than cocoa associated with full rate conventionally supplied T. superba. This may be attributed to (1) more favorable light conditions under these taller shade seedlings and (2) the internal use of nutrients associated with exponentially supplied T. superba seedlings, which lowered stress on native soil resources. The latter is corroborated with our findings on soil fertility status. This strategy focused on reducing fertilizer inputs and developing precise plant nutrition technology for on-farm use. Our findings suggest that shade seedlings under steady state nutrition can mitigate early growth competition in the field.

Nursery practices increase seedling performance on nutrient-poor soils in Swietenia humilis

“…Despite the lack of reports on this particular species, the favorable effects of exponential nutrient supply on growth, and other beneficial characteristics in the nursery have been examined by many authors (Qu et al 2003, Salifu & Timmer 2003, Salifu & Jacobs 2006, Isaac et al 2011, Duan et al 2013, Wang et al 2013. Timmer (1997) reported this technique has the advantage of supplying the nutrient amounts required at each stage of seedling exponential growth.…”

“…Top-pruning and exponential fertilization effects in the nursery have not been documented in S. humilis, although improvement in seedling quality has been reported for many other forest species (Cetina et al 1999, Isaac et al 2011, Wang et al 2013. In this study, we examined top-pruning and fertilization effects on S. humilis seedlings by respectively evaluating various morphological and physiological indices in the nursery, and a quality test trial on nutrient-poor soils.…”

Differential response of cocoa (Theobroma cacao) families to field establishment stress

“…, Isaac et al. ) and mulching (Adeyemi ). The roles of these in enhancing establishment in denuded areas in West Africa are however unclear.…”

“…Research on enhancing cocoa seedling survival in the field has generally focused on the beneficial roles of various methods of nursing and fertilization regimes (Oppong et al 2007, Isaac et al 2011) and mulching (Adeyemi 1999). The roles of these in enhancing establishment in denuded areas in West Africa are however unclear.…”

Sustainable Agroforestry Models for Proposed Food Production in Post-Mined Land Sites of South Sumatera

“…When perennial crops are involved in mature agroforestry systems, physiological and morphological differences between trees and perennial crops, such as stratified rooting zones, may reduce belowground competition as reported by several researchers. Applying fertilizer to the shade trees during nursery phase of perennial crop can mitigate early growth competition in the field when the crop is transplanted in the trees-cocoa agroforestry system [5]. Timber species may be promoted for the shade component of cacao plantations at the agroforestry system, due to their potential production and the fact that their presence does not negatively affect cocoa yields [6].…”