Journal Articles

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https://hub.ifdc.org/handle/20.500.14297/2086

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Browsing Journal Articles by Author "A.C. Franke"

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    Fertiliser Requirements for Balanced Nutrition of Cassava across Eight Locations in West Africa
    (2016) K.S. Ezui; A.C. Franke; Abdoulaye Mando; Benjamin Dzorgbenyui Kofi Ahiabor; F.M. Tetteh; J. Sogbedji; B.H. Janssen; Ken E. Giller
    Insufficient and unbalanced fertiliser use widens cassava yield gaps. We assessed the spatial variability of optimal fertiliser requirements of cassava for enhanced nutrient use efficiency and increased yield using the balanced nutrition approach of the QUEFTS model. Two datasets comprised of five fertiliser experiments conducted at eight locations across Southern Togo, Southern Ghana and Northern Ghana from 2007 to 2012 were used. The ratio of storage roots dry matter yield over the sum of available N, P and K expressed in crop nutrient equivalent from the soil and nutrient inputs was used as a proxy to estimate nutrient use efficiency. Nutrient use efficiencies of 20.5 and 31.7 kg storage roots dry matter per kilo crop nutrient equivalent were achieved at balanced nutrition at harvest index (HI) values of 0.50 and 0.65, respectively. N, P and K supplies of 16.2, 2.7 and 11.5 kg at an HI of 0.50, and 10.5, 1.9 and 8.4 kg at an HI of 0.65 were required to produce 1000 kg of storage roots dry matter. The corresponding optimal NPK supply ratios are 6.0–1.0–4.2 and 5.3–1.0–4.2. Nutrient use efficiencies decreased above yields of 77–93% of the maximum. Evaluation of the performance of blanket fertiliser rates recommended by national research services for cassava production resulted in average benefit:cost ratios of 2.4 ± 0.9, which will be unattractive to many farmers compared to 3.8 ± 1.1 for the balanced fertiliser rates. The indigenous soil supply of nutrients revealed that, at balanced nutrition, K was the most limiting nutrient to achieve storage roots yields up to 8 Mg dry matter ha−1 at most sites, whereas N and P were needed at greater yields. Dry weight of storage roots measured on the control plots in our researcher managed experiment ranged from 5.6 to 12.2 Mg ha−1, and were larger than the average weight in farmers’ fields in West Africa of 4 Mg ha−1. Substantial yield increase could be attained in the region with improved crop management and fertiliser requirements formulation on the basis of balanced nutrition.
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    Water and Radiation Use Efficiencies Explain the Effect of Potassium on the Productivity of Cassava
    (2016-11-15) K.S. Ezui; A.C. Franke; P.A. Leffelaar; Abdoulaye Mando; J. van Heerwaarden; Joaquin Sanabria; J. Sogbedji; Ken E. Giller
    We studied the effects of potassium (K) and its interactions with nitrogen (N), phosphorus (P) and harvest time on the productivity, water use efficiency (WUE) and radiation use efficiency (RUE) of cassava under rain-fed conditions. A field experiment was conducted during two consecutive years on K-deficient soils in Djakakope and on relatively K-rich soils in Sevekpota in Southern Togo, West Africa. Fifteen fertiliser combinations involving K and N rates of 0, 50 and 100 kg ha−1 each, and P rates of 0, 20 and 40 kg ha 1 were tested. Monthly measurements of leaf area index from 3 to 11 months after planting and daily weather data were used to estimate light interception, RUE, potential water transpiration and WUE of cassava. Overall WUE was 3.22 g dry matter kg−1 water transpired and RUE was 1.16 g dry matter MJ−1 intercepted photosynthetic active radiation (PAR). On the K-deficient soils, application of K increased WUE and RUE by 36–41% compared with 2.81 g dry matter kg−1 water transpired and 0.92 g dry matter MJ−1 intercepted PAR achieved without K, respectively. However, the effect of K on cassava growth depended on N availability. Applications of N had relatively weak effects on RUE and WUE, but induced a positive correlation between RUE/WUE and K mass fractions in the plant, and increased the cumulative amount oflightintercepted by 11–51%, and the cumulative amount of water transpired through increased leaf area by 13–61%. No significant effect of P on WUE and RUE was observed. Increased cassava yields could be achieved under rain-fed conditions in West Africa through enhanced K management to increase RUE and WUE, along with sufficient N supply for improved light interception and water transpiration by the crop.