Dose-response models to guide site-specific nutrient management and lessons for fertiliser trial design in sub-Saharan Africa

2021 ◽  
pp. 1-18
Author(s):  
Gudeta W. Sileshi
Keyword(s):  
Dose Response ◽  
Trial Design ◽  
Nutrient Management ◽  
Sub Saharan Africa ◽  
Yield Response ◽  
Accurate Estimation ◽  
Site Specific ◽  
Response Models ◽  
Nutrient Levels ◽  
Sub Saharan

Summary Optimisation of fertiliser use and site-specific nutrient management are increasingly becoming critical because of the growing need to balance agricultural productivity with the growing demand for food and environmental concerns. Trials to determine responses of crops to fertilisers have been widely conducted in sub-Saharan Africa (SSA) with increasing emphasis on the development of economically optimum rates (EORs). Computation of EORs depends on accurate estimation of both the optimum nutrient rate and the agronomic maximum yield response; however, estimation of nutrient-response parameters and EORs is beset by a number of problems. Therefore, the objectives of this paper were to (1) point out common problems in the development and use of nutrient dose-response models and (2) provide corrective measures to facilitate future trial design and data analysis. This review outlines the underlying assumptions, strengths and limitations of the various response functions in order to facilitate informed choices by practitioners. Using specific examples, it also shows that (1) the commonly used trial designs do not allow examination of interactions between two or more nutrients and (2) trial designs with ≤5 nutrient levels and wide spacing between the levels result in large uncertainty in dose-response parameters. The key recommendations emerging from the review are as follows: (1) factorial designs and response surface models should be used more widely to address interactions between nutrients; (2) a minimum of six carefully spaced nutrient levels should be used to correctly estimate dose-response parameters; and (3) when locating field trials, Reference Soil Groups and cropping history should be carefully considered to produce site-specific EORs.

scholarly journals Farmers’ Participatory Site Specific Nutrient Management in Gangetic Tidal Floodplain Soil for High Yielding Boro Rice (Oryza Sativa L.)

2013 ◽  
Vol 11 (1) ◽  
pp. 8-14 ◽  
Author(s):  
DK Nath ◽  
F Haque ◽  
F Amin ◽  
M Sh Islam ◽  
MA Saleque
Keyword(s):  
Oryza Sativa ◽  
Nutrient Management ◽  
Oryza Sativa L ◽  
Block Design ◽  
Yield Response ◽  
Management Approach ◽  
Nitrogen And Phosphorus ◽  
Floodplain Soil ◽  
Site Specific ◽  
A Site

Site Specific Nutrient Management (SSNM) trials were conducted for irrigated, transplanted and high yielding rice (Oryza sativa L.) during Boro season 2012. Four treatments (NPK, PK, NK, and NP) were applied in a randomized complete block design to assess the effects of indigenous nutrient elements on rice yield and yield components. The trials were conducted so as to develop a site specific nutrient management approach for the farmers of Gangtic Tidal Floodplain ecosystem. The highest grain-yield of 5.64 t ha-1 was observed in NPK treatment, which gave 9.0, 34.4 and 50.7% higher yields than those of NP, NK and PK, respectively. The response to indigenous K was remarkable and it gave the second highest yield (5.13 t ha-1). The yield response to indigenous N was very poor and the lowest yield was found in N omission treatment (2.78 t ha-1). The response to indigenous P was also poor (3.7 t ha-1). This result shows that nitrogen and phosphorus are the most vibrant factors to increase yield since omission of N and P had significant impact on yield during Boro season. Use of N, P and K at 128.7, 8.08 and 12.78 kg, respectively could be recommended for growing BRRI dhan47 in Boro season. It could save P and K nutrient by 55.11 and 75.89 % compared to that of NPK treatment, respectively. DOI: http://dx.doi.org/10.3329/agric.v11i1.15236 The Agriculturists 2013; 11(1) 8-14

scholarly journals Nitrous Oxide Emissions from Smallholders’ Cropping Systems in Sub-Saharan Africa

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Shaankua E. Lemarpe ◽  
Collins M. Musafiri ◽  
Joseph M. Macharia ◽  
Milka N. Kiboi ◽  
Onesmus K. Ng’etich ◽  
...  
Keyword(s):  
Climate Change ◽  
Management Practices ◽  
Cropping Systems ◽  
Empirical Studies ◽  
Sub Saharan Africa ◽  
N2o Emissions ◽  
Ozone Layer Depletion ◽  
Site Specific ◽  
Emissions Mitigation ◽  
Sub Saharan

Increased concentration of atmospheric nitrous oxide (N2O), a potent greenhouse gas (GHG), is of great concern due to its impact on ozone layer depletion leading to climate change. Ozone layer depletion allows penetration of ultraviolet radiations, which are hazardous to human health. Climate change culminates in reduced food productivity. Limited empirical studies have been conducted in Sub-Saharan Africa (SSA) to quantify and understand the dynamics of soil N2O fluxes from smallholder cropping systems. The available literature on soil N2O fluxes in SSA is limited; hence, there is a pressing need to consolidate it to ease mitigation targeting and policy formulation initiatives. We reviewed the state of N2O emissions from selected cropping systems, drivers that significantly influence N2O emissions, and probable soil N2O emissions mitigation options from 30 studies in SSA cropping systems have been elucidated here. The review outcome indicates that coffee, tea, maize, and vegetables emit N2O ranging from 1 to 1.9, 0.4 to 3.9, 0.1 to 4.26, and 48 to 113.4 kg N2O-N ha-1 yr−1, respectively. The yield-scaled and N2O emissions factors ranged between 0.08 and 67 g N2O-N kg−1 and 0.01 and 4.1%, respectively, across cropping systems. Soil characteristics, farm management practices, and climatic and environmental conditions were significant drivers influencing N2O emissions across SSA cropping systems. We found that site-specific soil N2O emissions mitigation measures are required due to high variations in N2O drivers across SSA. We conclude that appropriate fertilizer and organic input management combined with improved soil management practices are potential approaches in N2O emissions mitigation in SSA. We recommend that (i) while formulating soil N2O emissions mitigation approaches, in SSA, policymakers should consider site-specific targeting approaches, and (ii) more empirical studies need to be conducted in diverse agroecological zones of SSA to qualify various mitigation options on N2O emissions, yield-scaled N2O emissions, and N2O emission factors which are essential in improving national and regional GHG inventories.

scholarly journals The Future of Low-emission Sustainable Cereal Intensification in SSA

2021 ◽  
Author(s):  
Kindie Tesfaye ◽  
Marloes van Loon ◽  
Hein ten Berge ◽  
Renske Hijbeek ◽  
Dawit Solomon ◽  
...  
Keyword(s):  
Nutrient Management ◽  
Crop Protection ◽  
Ghg Emissions ◽  
Sub Saharan Africa ◽  
Ghg Emission ◽  
Pests And Diseases ◽  
Low Emission ◽  
Cereal Production ◽  
Sub Saharan ◽  
Area Expansion

This brief summarizes results of three recent studies that assessed whether Sub Saharan Africa (SSA) can be self-sufficient in cereals (maize, rice, wheat, sorghum, and millet) while minimizing GHG emission by 2050 under different scenarios of intensification on existing cereal area, as opposed to crop land area expansion. The results from three studies suggest that intensification of cereal production with sufficient and efficient use of fertilizers could lead to the lowest GHG emissions among the scenarios studied in future cereal productions in SSA. However, this requires excellent agronomy, including the use of well-adapted cultivars, proper planting densities, good nutrient management and crop protection against weeds, pests, and diseases. It should also be noted that intensification of cereal production may also have additional benefits, including improving the economic profitability for smallholders in SSA.

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