Good soil management can reduce dietary zinc deficiency in Zimbabwe

Abstract Background Dietary zinc (Zn) deficiency is widespread in sub-Saharan Africa (SSA) with adverse impacts on human health. Agronomic biofortification with Zn fertilizers and improved soil fertility management, using mineral and organic nutrient resources, has previously been shown to increase Zn concentration of staple grain crops, including maize. Here, we show the potential of different soil fertility management options on maize crops to reduce dietary Zn deficiency in Zimbabwe using secondary data from a set of surveys and field experiments. Methods An ex-ante approach was used, informed by published evidence from studies in three contrasting smallholder production systems in Zimbabwe. To estimate current Zn deficiency in Zimbabwe, data on dietary Zn supply from non-maize sources from the Global Expanded Nutrient Supply (GENuS) data set were linked to maize grain Zn composition observed under typical current soil fertility management scenarios. Results A baseline dietary Zn deficiency prevalence of 68% was estimated from a reference maize grain Zn composition value of 16.6 mg kg−1 and an estimated dietary Zn intake of 9.3 mg capita−1 day−1 from all food sources. The potential health benefits of reducing Zn deficiency using different soil fertility management scenarios were quantified within a Disability Adjusted Life Years (DALYs) framework. A scenario using optimal mineral NPK fertilizers and locally available organic nutrient resources (i.e. cattle manure and woodland leaf litter), but without additional soil Zn fertilizer applications, is estimated to increase maize grain Zn concentration to 19.3 mg kg−1. This would reduce the estimated prevalence of dietary Zn deficiency to 55%, potentially saving 2238 DALYs year−1. Universal adoption of optimal fertilizers, to include soil Zn applications and locally available organic leaf litter, is estimated to increase maize grain Zn concentration to 32.4 mg kg−1 and reduce dietary Zn deficiency to 16.7%, potentially saving 9119 DALYs year−1. Potential monetized yield gains from adopting improved soil fertility management range from 49- to 158-fold larger than the potential reduction in DALYs, if the latter are monetized using standard methods. Conclusion Farmers should be incentivized to adopt improved soil fertility management to improve both crop yield and quality.

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Good soil management can reduce dietary zinc deficiency in Zimbabwe.

10.31220/agrirxiv.2021.00033 ◽

2021 ◽

Author(s):

Muneta G. Manzeke-Kangara ◽

Edward J. M. Joy ◽

Florence Mtambanengwe ◽

Prosper Chopera ◽

Michael J. Watts ◽

...

Keyword(s):

Soil Fertility ◽

Zn Deficiency ◽

Soil Fertility Management ◽

Management Scenarios ◽

Fertility Management ◽

Zn Concentration ◽

Maize Grain ◽

Soil Zn ◽

Nutrient Resources ◽

Grain Zn Concentration

Abstract Dietary zinc (Zn) deficiency is widespread in sub-Saharan Africa (SSA) with adverse impacts on human health. Agronomic biofortification with Zn fertilizers and improved soil fertility management, using mineral and organic nutrient resources, has previously been shown to increase Zn concentration of staple grain crops, including maize. Here, we show the potential of different soil fertility management options on maize crops to reduce dietary Zn deficiency in Zimbabwe using secondary data from a set of survey and field experiments. An ex-ante approach was used, informed by published evidence from studies in three contrasting smallholder production systems in Zimbabwe. To estimate current Zn deficiency in Zimbabwe, data on dietary Zn supply from non-maize sources from the Global Expanded Nutrient Supply (GENuS) data set were linked to maize grain Zn composition observed under typical current soil fertility management scenarios. A baseline dietary Zn deficiency prevalence of 68% was estimated from a reference maize grain Zn composition value of 16.6 mg kg-1 and an estimated dietary Zn intake of 9.3 mg capita-1 day-1 from all food sources. The potential health benefits of reducing Zn deficiency using different soil fertility management scenarios were quantified within a Disability Adjusted Life Years (DALYs) framework. A scenario using optimal mineral NPK fertilizers and locally available organic nutrient resources (i.e. cattle manure and leaf litter), but without additional soil Zn fertilizer applications, is estimated to increase maize grain Zn concentration to 19.3 mg kg-1. This would reduce the estimated prevalence of dietary Zn deficiency to 55%, potentially saving 2,238 DALYs year-1. Universal adoption of optimal fertilizers, to include soil Zn applications and locally available organic leaf litter, is estimated to increase maize grain Zn concentration to 32.4 mg kg-1 and reduce dietary Zn deficiency to 16.7%, potentially saving 9,119 DALYs year-1. Potential monetized yield gains from adopting improved soil fertility management range from 49- to 158-fold larger than the potential reduction in DALYs, if the latter are monetized using standard methods. Farmers should be incentivized to adopt improved soil fertility management to improve both crop yield and quality.

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IRRIGATION MANAGEMENT RISKS AND ZN FERTILIZATION NEEDS IN ZN BIOFORTIFICATION BREEDING IN LOWLAND RICE

Experimental Agriculture ◽

10.1017/s0014479717000084 ◽

2017 ◽

Vol 54 (3) ◽

pp. 382-398 ◽

Cited By ~ 1

Author(s):

F.H.C. RUBIANES ◽

B.P. MALLIKARJUNA SWAMY ◽

S.E. JOHNSON-BEEBOUT

Keyword(s):

Water Management ◽

Field Experiment ◽

Irrigation Management ◽

Grain Filling ◽

Greenhouse Experiment ◽

Zn Deficiency ◽

Zn Uptake ◽

Zn Concentration ◽

Soil Zn ◽

Grain Zn Concentration

SUMMARYAs zinc (Zn) fertilizer and water management affect the expression of Zn-enriched grain traits in rice, we studied the effect of Zn fertilizer and water management on Zn uptake and grain yield of different biofortification breeding lines and the possible biases in selection for high grain Zn content. The first field experiment showed that longer duration genotypes had higher grain Zn uptake rate than shorter duration genotypes during grain filling. In the first greenhouse experiment, neither application of Zn fertilizer at mid-tillering nor application at flowering significantly increased the grain Zn concentration. In the second greenhouse experiment, application of alternate wetting and drying (AWD) significantly increased the available soil Zn and plant Zn uptake but not grain Zn concentration. Terminal drying (TD) did not increase the available soil Zn or grain Zn contents. The second field experiment confirmed that differences in TD were not important in understanding differences between genotypes. Zn application is not always necessary to breeding trials unless there is a severe Zn deficiency and there is no need to carefully regulate TD prior to harvest.

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SEQUENCING INTEGRATED SOIL FERTILITY MANAGEMENT OPTIONS FOR SUSTAINABLE CROP INTENSIFICATION BY DIFFERENT CATEGORIES OF SMALLHOLDER FARMERS IN ZIMBABWE

Experimental Agriculture ◽

10.1017/s0014479714000131 ◽

2014 ◽

Vol 51 (1) ◽

pp. 17-41 ◽

Cited By ~ 12

Author(s):

H. NEZOMBA ◽

F. MTAMBANENGWE ◽

R. CHIKOWO ◽

P. MAPFUMO

Keyword(s):

Soil Fertility ◽

Crop Yields ◽

Smallholder Farmers ◽

Mineral Fertilizers ◽

Soil Productivity ◽

Soil Fertility Management ◽

Management Options ◽

Integrated Soil Fertility Management ◽

Fertility Management ◽

Maize Grain

SUMMARYResearch has proved that integrated soil fertility management (ISFM) can increase crop yields at the field and farm scales. However, its uptake by smallholder farmers in Africa is often constrained by lack of technical guidelines on effective starting points and how the different ISFM options can be combined to increase crop productivity on a sustainable basis. A 4-year study was conducted on sandy soils (<10% clay) on smallholder farms in eastern Zimbabwe to assess how sequencing of different ISFM options may lead to incremental gains in soil productivity, enhanced efficiency of resource use, and increase crop yields at field scale. The sequences were primarily based on low-quality organic resources, nitrogen-fixing green manure and grain legumes, and mineral fertilizers. To enable comparison of legume and maize grain yields among treatments, yields were converted to energy (kilocalories) and protein (kg) equivalents. In the first year, ‘Manure-start’, a cattle manure-based sequence, yielded 3.4 t ha−1of maize grain compared with 2.5 and 0.4 t ha−1under a woodland litter-based sequence (‘Litter-start’) and continuous unfertilized maize control, respectively. The ‘Manure-start’ produced 12 × 106kilocalories (kcal); significantly (p< 0.05) out-yielding ‘Litter start’ and a fertilizer-based sequence (‘Fertilizer-start’) by 50%. A soyabean-based sequence, ‘Soya-start’, gave the highest protein production of 720 kg against <450 kg for the other sequencing treatments. In the second year, the sequences yielded an average of 5.7 t ha−1of maize grain, producing over 19 × 106kcal and 400 kg of protein. Consequently, the sequences significantly out-performed farmers’ designated poor fields by ~ fivefold. In the third year, ‘Soya-start’ gave the highest maize grain yield of 3.7 t ha−1; translating to 1.5 and 3 times more calories than under farmers’ designated rich and poor fields, respectively. In the fourth year, ‘Fertilizer-start’ produced the highest calories and protein of 14 × 106kcal and 340 kg, respectively. Cumulatively over 4 years, ‘Manure-start’ and ‘Soya-start’ gave the highest calories and protein, out-performing farmers’ designated rich and poor fields. Sunnhemp (Crotalaria junceaL.)-based sequences, ‘Green-start’ and ‘Fertilizer-start’, recorded the highest gains in plant available soil P of ~ 4 mg kg−1over the 4-year period. Assessment of P agronomic efficiencies showed significantly more benefits under the ISFM-based sequences than under farmers’ designated rich and poor fields. Based on costs of seed, nutrients and labour, ‘Soya-start’ gave the best net present value over the 4 years, while ‘Fertilizer-start’ was financially the least attractive. Overall, the ISFM-based sequences were more profitable than fields designated as rich and poor by farmers. We concluded that ISFM-based sequences can provide options for farm-level intensification by different categories of smallholder farmers in Southern Africa.

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Wheat Rhizosphere Metagenome Reveals Newfound Potential Soil Zn-Mobilizing Bacteria Contributing to Cultivars’ Variation in Grain Zn Concentration

Frontiers in Microbiology ◽

10.3389/fmicb.2021.689855 ◽

2021 ◽

Vol 12 ◽

Author(s):

Sen Wang ◽

Zikang Guo ◽

Li Wang ◽

Yan Zhang ◽

Fan Jiang ◽

...

Keyword(s):

Calcareous Soils ◽

Zn Deficiency ◽

Metagenomic Sequencing ◽

Wheat Rhizosphere ◽

Zn Concentration ◽

Culture Independent ◽

The Status ◽

Soil Zn ◽

Interspecies Relations ◽

Grain Zn Concentration

An effective solution to global human zinc (Zn) deficiency is Zn biofortification of staple food crops, which has been hindered by the low available Zn in calcareous soils worldwide. Many culturable soil microbes have been reported to increase Zn availability in the laboratory, while the status of these microbes in fields and whether there are unculturable Zn-mobilizing microbes remain unexplored. Here, we use the culture-independent metagenomic sequencing to investigate the rhizosphere microbiome of three high-Zn (HZn) and three low-Zn (LZn) wheat cultivars in a field experiment with calcareous soils. The average grain Zn concentration of HZn was higher than the Zn biofortification target 40 mg kg–1, while that of LZn was lower than 40 mg kg–1. Metagenomic sequencing and analysis showed large microbiome difference between wheat rhizosphere and bulk soil but small difference between HZn and LZn. Most of the rhizosphere-enriched microbes in HZn and LZn were in common, including many of the previously reported soil Zn-mobilizing microbes. Notably, 30 of the 32 rhizosphere-enriched species exhibiting different abundances between HZn and LZn possess the functional genes involved in soil Zn mobilization, especially the synthesis and exudation of organic acids and siderophores. Most of the abundant potential Zn-mobilizing species were positively correlated with grain Zn concentration and formed a module with strong interspecies relations in the co-occurrence network of abundant rhizosphere-enriched microbes. The potential Zn-mobilizing species, especially Massilia and Pseudomonas, may contribute to the cultivars’ variation in grain Zn concentration, and they deserve further investigation in future studies on Zn biofortification.

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Impacts of Climate Variability and Soil Fertility Management Strategies on Maize Grain Yield on Ferrralsols in Coastal Western Africa

Journal of Renewable Agriculture ◽

10.12966/jra.06.04.2013 ◽

2013 ◽

Vol 1 (3) ◽

pp. 44

Author(s):

Kokou Adambounou Amouzou ◽

Keyword(s):

Climate Variability ◽

Soil Fertility ◽

Grain Yield ◽

Management Strategies ◽

Soil Fertility Management ◽

Fertility Management ◽

Maize Grain Yield ◽

Western Africa ◽

Maize Grain

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Zinc application enhances grain zinc density in genetically-zinc-biofortified wheat grown on a low-zinc calcareous soil

Journal of Scientific Agriculture ◽

10.25081/jsa.2018.v2.20181512 ◽

2018 ◽

pp. 107-110 ◽

Cited By ~ 1

Keyword(s):

Developing Countries ◽

Grain Yield ◽

Calcareous Soil ◽

Zn Deficiency ◽

Target Level ◽

Zn Concentration ◽

Grain Zinc ◽

Zn Availability ◽

Zinc Application ◽

Grain Zn Concentration

Human zinc (Zn) deficiency is a worldwide problem, especially in developing countries due to the prevalence of cereals in the diet. Among different alleviation strategies, genetic Zn biofortification is considered a sustainable approach. However, it may depend on Zn availability from soils. We grew Zincol-16 (genetically-Zn-biofortified wheat) and Faisalabad-08 (widely grown standard wheat) in pots with (8 mg kg−1) or without Zn application. The cultivars were grown in a low-Zn calcareous soil. The grain yield of both cultivars was significantly (P≤0.05) increased with that without Zn application. As compared to Faisalabad-08, Zincol-16 had 23 and 41% more grain Zn concentration respectively at control and applied rate of Zn. Faisalabad-08 accumulated about 18% more grain Zn concentration with Zn than Zincol-16 without Zn application. A near target level of grain Zn concentration (36 mg kg−1) was achieved in Zincol-16 only with Zn fertilisation. Over all, the findings clearly signify the importance of agronomic Zn biofortification of genetically Zn-biofortified wheat grown on a low-Zn calcareous soil.

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