Abstract
AimRecycling of cocoa pod husks has potential to contribute to mineral nutrition of cocoa. Yet little is known of the nutrient content and nutrient release patterns from the husks. The potassium (K) rich husks are usually left in heaps in cocoa plantations in Africa. We aimed to understand and quantify release patterns of K and other nutrients from husks under varying rainfall regimes and assessed the effects of partial decomposition and inundation on nutrient leaching rates.MethodsWe incubated chunks of cocoa pod husks to assess decomposition rates and we measured nutrient leaching rates from two sets of husk chunks: one set was placed in tubes that were submitted to simulated scheduled rainfall events while the second set was continuously inundated in beakers.ResultsDecomposition of husks followed a second-order exponential curve (k: 0.09 day−1; ageing constant: 0.43). Nutrient losses recorded within 25 days were larger and more variable for K (33%) than for other macronutrients released in this order: Mg > Ca ≈ P > N (less than 15%). Potassium leaching was mainly driven by rainfall frequency (P < 0.05) and reinforced by intense rainfall, especially at lower frequency. Under water-saturated conditions, 11% of K was leached out within 48 h from fresh husks compared with 92% from partially decayed husks.ConclusionSome initial decomposition of cocoa pod husks is required to expose K to intense leaching. As decomposition progresses, abundant K losses are to be expected under frequent and/or intense rainfall events.
Highlights
Cocoa (Theobroma cacao L.) is a major source of income for about 5 million small-scale farmers (Poelmans and Swinnen 2016)
We found that K losses followed curvilinear patterns for most leaching tubes, whereas trends were unclear for the other nutrients
Cocoa pod husks are rich in potassium and their potential contribution to tree nutrition is significant
Summary
Cocoa (Theobroma cacao L.) is a major source of income for about 5 million small-scale farmers (Poelmans and Swinnen 2016). A recent survey in the two countries that produce the most cocoa - Côte d’Ivoire and Ghana - set the average cocoa bean yields at 352 and 423 kg ha−1 respectively (Bymolt et al 2018). This is less than one-tenth of the potential yield of cocoa in West Africa (Zuidema et al 2005). The vast majority of cocoa plantations in West Africa is planted on cleared forest land whose nutrient capital accumulated over a long period (Ruf et al 2014). The fertility of the forest soil is progressively depleted by continuous nutrient offtakes in the cocoa beans with inadequate recycling or inputs of nutrients
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
