The fate of nitrogen during agricultural intensification in East Africa: nitrogen budgets in contrasting agroecosystems
The intensification of agricultural systems in sub-Saharan Africa (SSA) is necessary to reduce poverty and improve food security, but increased nutrient applications in smallholder systems could have negative consequences for water quality, greenhouse gas emissions, and air quality. We tracked nitro...
| Main Authors: | , , , , , , , |
|---|---|
| Format: | Journal Article |
| Language: | Inglés |
| Published: |
American Geophysical Union
2023
|
| Subjects: | |
| Online Access: | https://hdl.handle.net/10568/132252 |
| _version_ | 1855526526793023488 |
|---|---|
| author | Tully, Katherine L. Hickman, J.E. Russo, T.A. Neill, C. Matata, P. Nyadzi, G. Mutuo, P. Palm, C.A. |
| author_browse | Hickman, J.E. Matata, P. Mutuo, P. Neill, C. Nyadzi, G. Palm, C.A. Russo, T.A. Tully, Katherine L. |
| author_facet | Tully, Katherine L. Hickman, J.E. Russo, T.A. Neill, C. Matata, P. Nyadzi, G. Mutuo, P. Palm, C.A. |
| author_sort | Tully, Katherine L. |
| collection | Repository of Agricultural Research Outputs (CGSpace) |
| description | The intensification of agricultural systems in sub-Saharan Africa (SSA) is necessary to reduce poverty and improve food security, but increased nutrient applications in smallholder systems could have negative consequences for water quality, greenhouse gas emissions, and air quality. We tracked nitrogen (N) inputs and measured maize (Zea mays) biomass, grain yields, N leaching, and nitric oxide (NO) and nitrous oxide fluxes from a clayey soil in Yala, Kenya and a sandy soil in Tumbi, Tanzania, with application rates of 0, 50, 75, 100, 150, and 200 kg N ha−1 yr−1 over two cropping seasons. Maize yields were 4.5 times higher in Yala than Tumbi, but yields plateaued at both sites with fertilizer applications at or above 100 kg N ha−1 yr−1. Partial N budgets in Yala were typically negative, meaning more N was exported in maize biomass plus grain or lost from the system than was added in fertilizer. In Tumbi, N budgets were negative at lower fertilizer levels but positive at higher fertilizer levels. At both sites most (96%) of the N was lost through maize biomass/grain removal and N leaching. Fertilizer additions at or less than 50 kg N ha−1 yr−1 on these two contrasting sites resulted in minor gaseous N losses, and fertilizer additions less than 200 kg N ha−1 yr−1 caused relatively little change to N leaching losses. This indicates that the modest increases in fertilizer use required to improve maize yields will not greatly increase cropland N losses.
Plain Language Summary
Crop yields in smallholder agriculture across sub-Saharan Africa are low but could be increased by greater applications of nitrogen fertilizer. However, greater use of nitrogen fertilizer creates potential for higher emissions of nitrogen trace gases and nitrogen leaching losses. This study added nitrogen fertilizer doses (0, 50, 75, 100, 150, and 200 kg of nitrogen per hectare) to maize cropland in two smallholder farming sites, one on clay-rich soils in Kenya and one on sandy soils in Tanzania. It tracked removal of nitrogen fertilizer via harvested maize and losses as nitrous oxide (a greenhouse gas), NO (an air pollutant), and leaching of soil solution. Yields were 4.5 times higher on the clayey soil; yields plateaued at nitrogen application above 100 kg per hectare. Leaching losses far exceeded gaseous losses at both sites: 96% of nitrogen was removed in harvested crops and soil solution. Nitrogen additions at or below 50 kg of nitrogen per hectare led to minor increases in gaseous nitrogen losses and additions less than 200 kg of nitrogen per hectare did not increase soil solution losses. This indicates that the modest increases in fertilizer use required to improve maize yields will not greatly increase cropland nitrogen losses. |
| format | Journal Article |
| id | CGSpace132252 |
| institution | CGIAR Consortium |
| language | Inglés |
| publishDate | 2023 |
| publishDateRange | 2023 |
| publishDateSort | 2023 |
| publisher | American Geophysical Union |
| publisherStr | American Geophysical Union |
| record_format | dspace |
| spelling | CGSpace1322522025-11-11T10:18:54Z The fate of nitrogen during agricultural intensification in East Africa: nitrogen budgets in contrasting agroecosystems Tully, Katherine L. Hickman, J.E. Russo, T.A. Neill, C. Matata, P. Nyadzi, G. Mutuo, P. Palm, C.A. agriculture intensification sub-saharan africa food security smallholders east africa The intensification of agricultural systems in sub-Saharan Africa (SSA) is necessary to reduce poverty and improve food security, but increased nutrient applications in smallholder systems could have negative consequences for water quality, greenhouse gas emissions, and air quality. We tracked nitrogen (N) inputs and measured maize (Zea mays) biomass, grain yields, N leaching, and nitric oxide (NO) and nitrous oxide fluxes from a clayey soil in Yala, Kenya and a sandy soil in Tumbi, Tanzania, with application rates of 0, 50, 75, 100, 150, and 200 kg N ha−1 yr−1 over two cropping seasons. Maize yields were 4.5 times higher in Yala than Tumbi, but yields plateaued at both sites with fertilizer applications at or above 100 kg N ha−1 yr−1. Partial N budgets in Yala were typically negative, meaning more N was exported in maize biomass plus grain or lost from the system than was added in fertilizer. In Tumbi, N budgets were negative at lower fertilizer levels but positive at higher fertilizer levels. At both sites most (96%) of the N was lost through maize biomass/grain removal and N leaching. Fertilizer additions at or less than 50 kg N ha−1 yr−1 on these two contrasting sites resulted in minor gaseous N losses, and fertilizer additions less than 200 kg N ha−1 yr−1 caused relatively little change to N leaching losses. This indicates that the modest increases in fertilizer use required to improve maize yields will not greatly increase cropland N losses. Plain Language Summary Crop yields in smallholder agriculture across sub-Saharan Africa are low but could be increased by greater applications of nitrogen fertilizer. However, greater use of nitrogen fertilizer creates potential for higher emissions of nitrogen trace gases and nitrogen leaching losses. This study added nitrogen fertilizer doses (0, 50, 75, 100, 150, and 200 kg of nitrogen per hectare) to maize cropland in two smallholder farming sites, one on clay-rich soils in Kenya and one on sandy soils in Tanzania. It tracked removal of nitrogen fertilizer via harvested maize and losses as nitrous oxide (a greenhouse gas), NO (an air pollutant), and leaching of soil solution. Yields were 4.5 times higher on the clayey soil; yields plateaued at nitrogen application above 100 kg per hectare. Leaching losses far exceeded gaseous losses at both sites: 96% of nitrogen was removed in harvested crops and soil solution. Nitrogen additions at or below 50 kg of nitrogen per hectare led to minor increases in gaseous nitrogen losses and additions less than 200 kg of nitrogen per hectare did not increase soil solution losses. This indicates that the modest increases in fertilizer use required to improve maize yields will not greatly increase cropland nitrogen losses. 2023-07 2023-10-13T14:02:04Z 2023-10-13T14:02:04Z Journal Article https://hdl.handle.net/10568/132252 en Open Access application/pdf American Geophysical Union Tully, K.L., Hickman, J.E., Russo, T.A., Neill, C., Matata, P., Nyadzi, G., ... & Palm, C.A. (2023). The fate of nitrogen during agricultural intensification in East Africa: nitrogen budgets in contrasting agroecosystems. Journal of Geophysical Research: Biogeosciences, 128(7): e2022JG007128, 1-22. |
| spellingShingle | agriculture intensification sub-saharan africa food security smallholders east africa Tully, Katherine L. Hickman, J.E. Russo, T.A. Neill, C. Matata, P. Nyadzi, G. Mutuo, P. Palm, C.A. The fate of nitrogen during agricultural intensification in East Africa: nitrogen budgets in contrasting agroecosystems |
| title | The fate of nitrogen during agricultural intensification in East Africa: nitrogen budgets in contrasting agroecosystems |
| title_full | The fate of nitrogen during agricultural intensification in East Africa: nitrogen budgets in contrasting agroecosystems |
| title_fullStr | The fate of nitrogen during agricultural intensification in East Africa: nitrogen budgets in contrasting agroecosystems |
| title_full_unstemmed | The fate of nitrogen during agricultural intensification in East Africa: nitrogen budgets in contrasting agroecosystems |
| title_short | The fate of nitrogen during agricultural intensification in East Africa: nitrogen budgets in contrasting agroecosystems |
| title_sort | fate of nitrogen during agricultural intensification in east africa nitrogen budgets in contrasting agroecosystems |
| topic | agriculture intensification sub-saharan africa food security smallholders east africa |
| url | https://hdl.handle.net/10568/132252 |
| work_keys_str_mv | AT tullykatherinel thefateofnitrogenduringagriculturalintensificationineastafricanitrogenbudgetsincontrastingagroecosystems AT hickmanje thefateofnitrogenduringagriculturalintensificationineastafricanitrogenbudgetsincontrastingagroecosystems AT russota thefateofnitrogenduringagriculturalintensificationineastafricanitrogenbudgetsincontrastingagroecosystems AT neillc thefateofnitrogenduringagriculturalintensificationineastafricanitrogenbudgetsincontrastingagroecosystems AT matatap thefateofnitrogenduringagriculturalintensificationineastafricanitrogenbudgetsincontrastingagroecosystems AT nyadzig thefateofnitrogenduringagriculturalintensificationineastafricanitrogenbudgetsincontrastingagroecosystems AT mutuop thefateofnitrogenduringagriculturalintensificationineastafricanitrogenbudgetsincontrastingagroecosystems AT palmca thefateofnitrogenduringagriculturalintensificationineastafricanitrogenbudgetsincontrastingagroecosystems AT tullykatherinel fateofnitrogenduringagriculturalintensificationineastafricanitrogenbudgetsincontrastingagroecosystems AT hickmanje fateofnitrogenduringagriculturalintensificationineastafricanitrogenbudgetsincontrastingagroecosystems AT russota fateofnitrogenduringagriculturalintensificationineastafricanitrogenbudgetsincontrastingagroecosystems AT neillc fateofnitrogenduringagriculturalintensificationineastafricanitrogenbudgetsincontrastingagroecosystems AT matatap fateofnitrogenduringagriculturalintensificationineastafricanitrogenbudgetsincontrastingagroecosystems AT nyadzig fateofnitrogenduringagriculturalintensificationineastafricanitrogenbudgetsincontrastingagroecosystems AT mutuop fateofnitrogenduringagriculturalintensificationineastafricanitrogenbudgetsincontrastingagroecosystems AT palmca fateofnitrogenduringagriculturalintensificationineastafricanitrogenbudgetsincontrastingagroecosystems |