Wheat nutrient response functions for the East Africa highlands

Cyamweshi, Athanase R.; Nabahungu, Léon; Senkoro, Catherine J.; Kibunja, C.N.; Mukuralinda, Athanase; Kaizzi, Kayuki C.; Mvuyekure, Simon Martin; Kayumba, John; Ndung'u-Magiroi, Keziah Wairimu; Koech, M. N.; Wortmann, Charles S.

doi:10.1007/s10705-018-9912-z

Cited by 18 publications

(19 citation statements)

References 19 publications

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“…Cyamweshi et al. () found that 50% of the MgSZnB rates used in this study were sufficient to achieve 90% of the potential wheat ( Triticum aestivum ) response to these nutrients in Rwanda.…”

Section: Discussionmentioning

confidence: 64%

“…() suggested that decisions for financially constrained fertilizer use need to consider crop‐nutrient‐rate choices not only for rice but all crops important to the farmer for profit optimization. For example, the profit to cost ratio for high and low cost fertilizer applied at EOR to wheat ranged from 0.2 to 1.8 for N, 1.0 to 3.3 for P, and 0.5 to 2.0 for K (Cyamweshi et al., ). Similar ranges for bush and climbing bean ( Phaseolus vulgaris ) in Rwanda were, respectively, 1.0–3.3 and 1.1–3.6 for N, 1.4–4.1 and 1.7–5.0 for P, and 2.4–6.2 and 1.3–4.0 for K (Kaizzi et al., ).…”

Section: Discussionmentioning

confidence: 99%

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Lowland rice yield and profit response to fertilizer application in Rwanda

Nabahungu¹,

Cyamweshi

Kayumba

et al. 2020

Agronomy Journal

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Rice (Oryza sativa) production in Rwanda increased by 70% while yield ha −1 decreased during the past decade. Yield has biotic and abiotic constraints including inadequate nutrient supply. Yield response functions for N, P, and K were determined in eight marshlands grouped into four clusters. Additional treatment allowed for the diagnosis of response to Mg-S-Zn-B (MgSZnB). Rice grain yield with no fertilizer applied was 2.27 Mg ha −1 . Mean yield increases were 2.35, 1.53, and 1.71 Mg ha −1 with N, P, and K application, respectively. The mean economically optimal rates (EOR) were 58 to >150, 11-30, and 21-35 kg ha −1 for N, P, and K, respectively, depending on cluster and the cost of fertilizer. Yield responses to nutrient rates were similar across marshland clusters, and a single response function for each of P and K can serve all four clusters, while the response to N differed for Cluster B compared with A, BC, and C. Net returns to applied P and K were greater than for N, but the application of N is likely needed for such responses to P and K. The MgSZnB resulted in a mean grain yield increase of 1.72 Mg ha −1 with increases in all marshlands, but the information was not sufficient to determine which nutrients of MgSZnB were deficient or their optimal application rates. Fertilizer use can be very profitable for rice production in Rwanda. Profit can be enhanced with the application at less than EOR when fertilizer use is financially constrained.Abbreviations: AEZ, agro-ecological zone; CP, kg of rice grain required to equal the cost of 1 kg of nutrient use; EOR, economically optimal rate of nutrient application; MgSZnB, a diagnostic package of Mg, S, Zn, and B.

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Section: Discussionmentioning

confidence: 64%

Section: Discussionmentioning

confidence: 99%

Lowland rice yield and profit response to fertilizer application in Rwanda

Nabahungu¹,

Cyamweshi

Kayumba

et al. 2020

Agronomy Journal

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“…Results from previous studies in Ethiopia since 2000 indicated mean barley yield increases of 0.61 Mg ha −1 with 50 kg ha −1 N applied and increases of 0.27 Mg ha −1 with 10 kg ha −1 P applied (Dejene & Fetien, 2014; Mekonnen, 2005; Wortmann, 2018). Similar mean wheat yield increases were 0.90 Mg ha −1 with 50 kg ha −1 N applied for 31 trials, 0.57 Mg ha −1 with 10 kg ha −1 P applied for 21 trials, and 0.21 Mg ha −1 with 10 kg ha −1 K applied for five trials (Damota, 2003; Erkossa, Mamo, Kidane, & Abebe, 2000; Gashawbeza et al., 2003; Gemeda, 2009; Harfe, 2017; Shiferaw, 2003; Tarekegne, Tanner, Tessema, & Mandefro, 2000; Woyema, Bultosa, & Taa, 2012). Results reported for 20 trials conducted in Kenya, Rwanda, Tanzania, and Uganda since 2000 indicated mean wheat yield increases of 0.75 Mg ha −1 with 50 kg ha −1 N applied, 0.36 Mg ha −1 with 10 kg ha −1 P applied, and 0.28 Mg ha −1 with 10 kg ha −1 K applied (Cyamweshi et al., 2017).…”

Section: Introductionmentioning

confidence: 75%

Barley and wheat nutrient responses for Shewa, Ethiopia

et al. 2020

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Hulless barley (Hordeum vulgare L. var. nudum Hook. f.) and wheat (Triticum aestivum L.) are important crops for the highlands of western Shewa in Ethiopia. Information is scarce regarding the determination of fertilizer recommendations for barley and wheat with location specificity. On-farm trials were conducted to determine yield response to N and P and to diagnose K-Mg-S-Zn-B deficiencies in western Shewa. Grain yields were higher and responses to N and P were greater for these trials compared with results from earlier trials. Grain yield increases occurred with N application for all trials, ranging from 0.42 to 2.8 Mg ha −1 for barley and from 1.4 to 3.8 Mg ha −1 for wheat, fitting curvilinear to plateau or quadratic functions. Barley yield was maximized with 60 kg ha −1 N, and 98% of maximum yield was achieved with 50 kg ha −1 N, but wheat yield was projected to maximize with >100 kg ha −1 N. About 50% of the trials had yield increases with P application. Many farmers in this area are financially constrained regarding fertilizer use and can achieve a mean of 48% greater net return on their investment with the application at 50% rather than 100% of the rate to maximize profit per hectare. The yields and response to applied nutrients were generally less with earlier results compared with the current results, whereas the economically optimal rate of nutrient application or the rate expected to maximize net return per hectare to nutrient application was similar or slightly less for the earlier results. The profit opportunity with fertilizer use in western Shewa is great for N, less for P, and negligible for K-Mg-S-Zn-B.Abbreviations: CP, kilograms of barley or wheat required to equal the cost of 1 kg of nutrient applied; EOR, economically optimal nutrient rate; PCR, profit to cost ratio.

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“…Smallholder cropping systems are typically diverse, and each crop or intercrop has some level of profit potential for each nutrient that might be applied [2,3,[5][6][7][8][9][10][11][12][13]. Crop-nutrient response functions typically have a diminishing profit-to-cost ratio as the nutrient rate approaches the agronomic optimum.…”

Section: Fertilizer Use For Maximization Of the Farmer's Profitmentioning

confidence: 99%

“…For example, cereal yield response to N followed by P often has more profit potential than the application of K, secondary nutrients, and micronutrients. The application of several nutrients in a blend can result in increased yield compared to the application of fewer nutrients with the farmer's chosen combination of common fertilizers such as for wheat and maize production in Rwanda, but the profit potential is more often greater with common fertilizers [5,7,12,17]. Blending adds to the cost of nutrient supply, and blends often contain one or more nutrients that have low or no profit potential for the farmer.…”

Section: Blended and Compound Fertilizersmentioning

confidence: 99%

Fertilizer Use Issues for Smallholder Agriculture in Tropical Africa

Wortmann¹,

Esilaba²,

Kaizzi³

et al. 2020

Sustainable Crop Production

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Fertilizer is an essential input for wide-scale sustainable intensification of crop productivity in tropical Africa, but its use by smallholders is often financially constrained. Four fertilizer use issues are addressed. Smallholders need high net returns from their investments, with acceptable risk, which can be achieved with good crop-nutrient-rate choices made in consideration of the farmer's financial and agronomic context. Soil acidification, which is affected by crop N supply, is best managed with the use of slightly more acidifying but less costly common N fertilizer, e.g., urea, coupled with lime use compared with the use of more costly but less acidifying N fertilizer such as calcium ammonium nitrate. This chapter addresses the feasibility of tailored fertilizer blends for maximizing farmer profit with respect to the nutrient supply cost, the need for flexibility in nutrient application according to the farmer's context, and the weak justification for tailoring blends based on soil test results. The use of a wellformulated blends is justified in some cases, e.g., for some crops in Rwanda, but the supply of blends does not justify restricting the supply of common fertilizers. Farmers need to be aware that unregulated nontraditional products very often fail to provide the claimed benefits. Fertilizer use, sometimes with timely lime application, can be highly profitable with modest risk with good crop-nutrientrate choices, adequate free-market fertilizer supply, and avoiding products with unsubstantiated claims.

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Wheat nutrient response functions for the East Africa highlands

Cited by 18 publications

References 19 publications

Lowland rice yield and profit response to fertilizer application in Rwanda

Lowland rice yield and profit response to fertilizer application in Rwanda

Barley and wheat nutrient responses for Shewa, Ethiopia

Fertilizer Use Issues for Smallholder Agriculture in Tropical Africa

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