Towards understanding factors that govern fertilizer response in cassava: lessons from East Africa

Abstract

Information on fertilizer response in cassava in Africa is scarce. We conducted a series of onfarm and on-station trials in two consecutive years to quantify yield responses of cassava to mineral fertilizer in Kenya and Uganda and to evaluate factors governing the responses. Average unfertilized yields ranged from 4.2 to 25.7 t ha -1 between sites and years. Mineral fertilizer use increased yields significantly, but response to fertilizer was highly variable (-0.2 to 15.3 t ha -1 ). Average yield response per kg applied nutrient was 37, 168 and 45 and 106, 482 and 128 kg fresh yield per kg of applied N, P and K, respectively in 2004 and 2005. Fertilizer response was governed by soil fertility, rainfall and weed management, but was not influenced by variety, pest and disease pressure and harvest age. Relative N and K yields were positively correlated to SOC and exchangeable K, while response to fertilizer decreased on more fertile soils. Still, fertilizer response varied widely on low fertility soils (e.g. on soils with\10 g kg -1 SOC, responses ranged from -8.6 to 24.4 t ha -1 ), indicating strong interactions between factors governing fertilizer response. Response to fertilizer was reduced if total rainfall \1,500 mm or rainfall from 0 to 3 months after planting \400 mm. Fertilizer application promoted plant growth and resulted in a better soil coverage and reduced weed competition. Yields in fertilized fields were independent of weed management, unless growing conditions were unfavourable.

Effect of Chicken Manure Application on Cassava Biomass and Root Yields in Two Agro-Ecologies of Zambia

“…Four levels of chicken manure (0, 1.4, 2.8, 4.2 ton/ha) were evaluated against 100N-22P-83K kg/ha, a fertilizer rate generally recommended by Howeler, et al [8] for cassava and tried by Fermont, et al [9] in East Africa. This is to help fill the need for a blanket fertilizer recommendation for cassava in Zambia.…”

“…However, Vanlauwe, et al [6] emphasized that the production increase was a result of area expansion rather than an increase in yield per unit area. Available information also indicates that input use in cassava fields is very limited or absent among smallholder farms in SSA [7][8][9][10].…”

Cassava: The Drought, War and Famine Crop in a Changing World

“…Competition between cassava and weeds, for space, water and nutrients, can also significantly reduce cassava yields [135,144]. While weeds can be controlled with herbicides where available, they typically need to be removed by hand in subsistence farming systems, which represents a significant expenditure of time and energy [135].…”

“…The increase in area under cassava cultivation in Africa has primarily been on low quality soils, especially in East Africa [144]. As with most crops, application of fertilisers leads to improved growth and nutrition of cassava, with increased plant biomass, tuber number and overall yield [18,144,159].…”

Correlation of Growth Parameters with Yield of Two Cassava Varieties

“…However, the results and performance of important crops may be affected by genetic as well as vorius environmental factors which could be linked to inclement temperatures, water deficit, inefficient distribution of assimilates in favor of he root and time of harvest (Grant et al, 1985;Chang, 1991). The productivity of cassava is also limited by soil nutrient status, increased yield due to fertilizer application has been severaly reported (Fermont et al, 2010;.Okpara et al, 2010;Edet et al, 2013). In cassava, the result is closely associated with tuber diameter, size and weight (Ntawuruhunga and Dixon, 2010;Agahiu, 2011 compete for photosynthetic assimilates due to cassava unique simultaneous development of sinks organ (El-Sharkawy.…”