Yield variation of rainfed rice as affected by field water availability and N fertilizer use in central Benin

SUMMARYIn sub-Saharan Africa (SSA), rainfed agriculture is the dominant source of food production. Over the past 50 years much agronomic crop research has been undertaken, and the results of such work are used in formulating recommendations for farmers. However, since rainfall is highly variable across seasons the outcomes of such research will depend upon the rainfall characteristics of the seasons during which the work was undertaken. A major constraint that is faced by such research is the length of time for which studies could be continued, typically ranging between three and five years. This begs the question as to what extent the research was able to ‘sample’ the natural longer-term season-to-season rainfall variability. Without knowledge of the full implications of weather variability on the performance of innovations being recommended, farmers cannot be properly advised about the possible weather-induced risks that they may face over time. To overcome this constraint, crop growth simulation models such as the Agricultural Production Systems Simulator (APSIM) can be used as an integral part of field-based agronomic studies. When driven by long-term daily weather data (30+ years), such models can provide weather-induced risk estimates for a wide range of crop, soil and water management innovations for the major rainfed crops of SSA. Where access to long-term weather data is not possible, weather generators such as MarkSim can be used. This study demonstrates the value of such tools in climate risk analyses and assesses the value of the outputs in the context of a high potential maize production area in Kenya. MarkSim generated weather data is shown to provide a satisfactory approximation of recorded weather data at hand, and the output of 50 years of APSIM simulations demonstrate maize yield responses to plant population, weed control and nitrogen (N) fertilizer use that correspond well with results reported in the literature. Weather-induced risk is shown to have important effects on the rates of return ($ per $ invested) to N-fertilizer use which, across seasons and rates of N-application, ranged from 1.1 to 6.2. Similarly, rates of return to weed control and to planting at contrasting populations were also affected by seasonal variations in weather, but were always so high as to not constitute a risk for small-scale farmers. An analysis investigating the relative importance of temperature, radiation and water availability in contributing to weather-induced risk at different maize growth stages corresponded well with crop physiological studies reported in the literature.

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MAXIMIZING WATER AND N FERTILIZER USE EFFICIENCIES UNDER MAIZE CROP AT NORTH DELTA

Journal of Soil Sciences and Agricultural Engineering ◽

10.21608/jssae.2012.53319 ◽

2012 ◽

Vol 3 (1) ◽

pp. 27-39

Author(s):

H. A. Sonbol ◽

Z. M. El-Sirafy ◽

E. A. E. Gazia ◽

H. A. Shams El-Din ◽

Sahar H. Rashed

Keyword(s):

N Fertilizer ◽

Maize Crop ◽

Fertilizer Use ◽

N Fertilizer Use

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Effective management of N fertilizer use for wheat and barley production in a semi-arid environment

Plant Nutrition — from Genetic Engineering to Field Practice ◽

10.1007/978-94-011-1880-4_112 ◽

1993 ◽

pp. 525-528 ◽

Cited By ~ 1

Author(s):

Z. H. Xu ◽

D. E. Elliott

Keyword(s):

Arid Environment ◽

N Fertilizer ◽

Effective Management ◽

Fertilizer Use ◽

N Fertilizer Use ◽

Semi Arid

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Environmental effects of N fertilizer use ? An overview

Fertilizer Research ◽

10.1007/bf01048758 ◽

1990 ◽

Vol 26 (1-3) ◽

pp. 209-215 ◽

Cited By ~ 35

Author(s):

B. H. Byrnes

Keyword(s):

Environmental Effects ◽

N Fertilizer ◽

Fertilizer Use ◽

N Fertilizer Use

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Effectivity and Cost Efficiency of a Tax on Nitrogen Fertilizer to Reduce GHG Emissions from Agriculture

Atmosphere ◽

10.3390/atmos11060607 ◽

2020 ◽

Vol 11 (6) ◽

pp. 607

Author(s):

Andreas Meyer-Aurich ◽

Yusuf Nadi Karatay ◽

Ausra Nausediene ◽

Dieter Kirschke

Keyword(s):

Risk Aversion ◽

Field Experiments ◽

Function Analysis ◽

Ghg Emissions ◽

N Fertilizer ◽

Relative Advantage ◽

N2o Emissions ◽

Ghg Mitigation ◽

Fertilizer Use ◽

N Fertilizer Use

The use of nitrogen (N) fertilizer substantially contributes to greenhouse gas (GHG) emissions due to N2O emissions from agricultural soils and energy-intensive fertilizer manufacturing. Thus, a reduction of mineral N fertilizer use can contribute to reduced GHG emissions. Fertilizer tax is a potential instrument to provide incentives to apply less fertilizer and contribute to the mitigation of GHG emissions. This study provides model results based on a production function analysis from field experiments in Brandenburg and Schleswig-Holstein, with respect to risk aversion by calculating certainty equivalents for different levels of risk aversion. The model results were used to identify effective and cost-efficient options considering farmers’ risk aversion to reduce N fertilizer, and to compare the potential and cost of GHG mitigation with different N fertilizer tax schemes. The results show that moderate N tax levels are effective in reducing N fertilizer levels, and thus, in curbing GHG emissions at costs below 100 €/t CO2eq for rye, barley and canola. However, in wheat production, N tax has limited effects on economically optimal N use due to the effects of N fertilizer on crop quality, which affect the sale prices of wheat. The findings indicate that the level of risk aversion does not have a consistent impact on the reduction of N fertilizer with a tax, even though the level of N fertilizer use is generally lower for risk-averse agents. The differences in N fertilizer response might have an impact on the relative advantage of different crops, which should be taken into account for an effective implementation of a tax on N fertilizer.

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Optimizing nitrogen fertilizer use for more grain and less pollution

10.21203/rs.3.rs-361734/v1 ◽

2021 ◽

Author(s):

Keyu Ren ◽

Minggang Xu ◽

Rong Li ◽

Lei Zheng ◽

Shaogui Liu ◽

...

Keyword(s):

Crop Production ◽

Management Practices ◽

Application Rate ◽

N Fertilizer ◽

N Application ◽

Fertilizer Use ◽

Application Rates ◽

Operational Practices ◽

N Management ◽

N Fertilizer Use

Abstract Optimal nitrogen (N) management is critical for efficient crop production and agricultural pollution control. However, it is difficult to implement advanced management practices on smallholder farms due to a lack of knowledge and technology. Here, using 35,502 on-farm fertilization experiments, we demonstrated that smallholders in China could produce more grain with less N fertilizer use through optimizing N application rate. The yields of wheat, maize and rice were shown to increase between 10% and 19% while N application rates were reduced by 15–19%. These changes resulted in an increase in N use efficiency (NUE) by 32–46% and a reduction in N surplus by 40% without actually changing farmers’ operational practices. By reducing N application rates in line with official recommendations would not only save fertilizer cost while increasing crop yield, but at the same time reduce environmental N pollution in China. However, making progress towards further optimizing N fertilizer use to produce more grain with less pollution would require managements to improve farmers’ practices which was estimated to cost about 11.8 billion US dollars to implement.

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Determining the optimal nitrogen rate for summer maize in China by integrating agronomic, economic, and environmental aspects

Biogeosciences ◽

10.5194/bg-11-3031-2014 ◽

2014 ◽

Vol 11 (11) ◽

pp. 3031-3041 ◽

Cited By ~ 19

Author(s):

G. L. Wang ◽

Y. L. Ye ◽

X. P. Chen ◽

Z. L. Cui

Keyword(s):

Grain Yield ◽

Economic Benefit ◽

Maximum Yield ◽

N Fertilizer ◽

Environmental Cost ◽

Environmental Costs ◽

Net Benefit ◽

Summer Maize ◽

Fertilizer Use ◽

N Fertilizer Use

Abstract. The concept of high yield with a goal of minimum environmental cost has become widely accepted. However, the trade-offs and complex linkages among agronomic, economic, and environmental factors are not yet well understood. In this study, reactive nitrogen (Nr) losses were estimated using an empirical model, and an economic indicator and an evaluation model were used to account for the environmental costs of N fertilizer production and use. The minimum N rate to achieve the maximum yield benefit (agronomically optimal N rate), maximum economic benefit (economically optimal N rate: economic benefit was defined as yield benefit minus N fertilizer cost), and maximum net benefit (ecologically optimal N rate: net benefit was defined as yield benefit minus N fertilizer and environmental costs) were estimated based on 91 on-farm experiment sites with five N levels for summer maize production on the North China Plain. Across all experimental sites, the agronomically, economically, and ecologically optimal N rates (Nagr, Neco, and Necl, respectively) averaged 289, 237, and 171 kg N ha−1, respectively. Necl management increased net benefit by 53% with a 46% decrease in total environmental costs, and a 51% decrease in Nr loss intensity from N fertilizer use (47, 65, and 38% for N2O emission, N leaching, and NH3 volatilization, respectively) and maintained grain yield, compared with Nagr management. Compared with Neco management, Necl increased net benefit by 12%, with a 31% decrease in total environmental costs and a 33% decrease in Nr loss intensity from N fertilizer use, and maintained economic benefit and grain yield. No differences in Necl were observed between soil types or years, but significant variation among counties was revealed. Necl increased with the increase in N-derived yield with an R2 of 0.83. In conclusion, Necl was primarily affected by N-derived yield and could enhance profitability as well as reduce Nr losses associated with the maize grain yield.

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Phosphorus concentrations into a subtropical lake strongly influence nitrogen accumulation, nitrogen export, and Chl a concentrations

Hydrobiologia ◽

10.1007/s10750-021-04673-z ◽

2021 ◽

Author(s):

R. Eugene Turner ◽

James M. Lee ◽

Charles S. Milan ◽

Erick M. Swenson

Keyword(s):

Algal Blooms ◽

Nitrogen Concentration ◽

N Fertilizer ◽

Freshwater Lake ◽

Nitrogen Accumulation ◽

Fertilizer Use ◽

Chl A ◽

Total Nitrogen Concentration ◽

P Fertilizer ◽

N Fertilizer Use

AbstractWe measured water quality monthly for 22 years in water entering, within, and exiting a 65 km2 shallow polymictic and eutrophic freshwater lake in the northern Gulf of Mexico. Fertilizer use in the watershed is the dominate source of phosphorous (P) going into the lake and controls the lake’s P concentrations, but nitrogen (N) fertilizer use was not related to total nitrogen concentration in the lake. Half of the particulate P entering the lake is trapped within it and there is a net accumulation of N that appears to be from the stimulation of nitrogen fixation. The lake’s concentration of Chlorophyll a (µg Chl a l−1) and increase in N in the lake was directly related to the concentration of P in water entering the lake. Variations in the Chl a concentration within a freshwater lake downstream are also directly related to the annual use of P fertilizer, but not to N fertilizer use. Reducing agriculture-sourced P runoff will lower (but not eliminate) both the frequency of algal blooms within Lac des Allemands and the amount of N delivered to the estuary.

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