Your search found 8 records
1 Nangia, Vinay; Du, Jian Tao; Ahmad, Mobin-ud-Din; Yan, Changrong. 2007. Modeling field-scale effects of conservation agriculture practices on soil water balance in the dryland regions of the Yellow River Basin, China. Paper presented at the 3rd International Yellow River Forum, Dongying, China, Oct 16-18, 2007. 12p.
Crop management ; Maize ; Tillage ; Soil water ; Water balance ; Simulation models ; Decision support tools ; River basins ; Erosion ; Zero tillage ; Mulching / China / Yellow River Basin / Shou Yang County
(Location: IWMI HQ Call no: IWMI 630 G592 NAN Record No: H040740)
Soil erosion by water is a severe problem for sustainability of agricultural systems in the dryland regions of the Yellow River Basin. Conservation agriculture (featuring reduced or zero tillage, mulch retention, crop rotations and cover crops) offers a possible solution. Conservation agriculture systems typically result in increased crop water availability, agro-ecosystem productivity and reduced soil erosion. To evaluate the potential of conservation agriculture to improve soil water balance and agricultural productivity, the DSSAT crop model was calibrated using the data of field experiment in Shou Yang County in the semi-arid northeastern part of the ellow River Basin. Its average annual precipitation is 472mm -75% of which falls during the rowing season. The site had a maize-fallow-maize rotation. We used two crop seasons-2005 and 2006 data from four treatments for calibration and analyses. The treatments were: conventional tillage (CT), no-till with straw mulching (NTSM), all-straw with return till (ASRT) and 1/3rd residue left with rolling till (RRT). The calibration results gave satisfactory agreement between field observed and model predicted values for crop yield and soil moisture contents for the 150cm soil profile for all treatments with difference between observed and predicted values being in the range of 3-25% for maize yield and RMSE in the range of 0.14-0.19cm3/cm3 for observed average soil moisture content. The predicted water productivity for the four treatments during dry year (precipitation 39% less than normal) was 1.59, 1.78, 1.67 and 1.52 kg/m3. and 1.70, 1.71, 1.71 and 1.70kg/m3 during the normal precipitation year (424.8 mm) for CT, NTSM, ASRT and RRT treatments, respectively. During the dry year, CT treatment produced highest ET (226mm) but NTSM treatment produced the highest crop yield (5736kg/ha)-suggesting that evaporative losses from CT treatment were higher than other NTSM treatment. During normal precipitation year, however, CT treatment produced highest ET (326mm) along with highest crop yield (6335kg/ha). During dry year, predicted moisture storage (_S) in the 150cm soil profile increased by 60% more for NTSM treatment compared to CT treatment. During normal precipitation fallow period, NTSM treatment predicted _S decreased by 63% less than CT treatment. These preliminary results are based on a two-year dataset and further long term analyses need to be carried out for improving the understanding of the conservation agriculture cropping systems in the Yellow River Basin.
2 Nangia, Vinay; de Fraiture, Charlotte; Turral, Hugh. 2008. Water quality implications of raising crop water productivity. Agricultural Water Management, 95(7):825-835.
Irrigated farming ; Crop production ; Water requirements ; Water management ; Water quality ; Productivity ; Nitrogen ; Simulation models ; Decision Support Systems ; Soil water ; Water balance ; Fertilizers / USA / Florida
(Location: IWMI HQ Call no: IWMI 631.7.1 G430 NAN Record No: H040741)
Because of a growing and more affluent population, demand for agricultural products will increase rapidly over the coming decades, with serious implications for agricultural water demand. Symptoms of water scarcity are increasingly apparent, threatening ecosystem services and the sustainability of food production. Improved water productivity will reduce the additional water requirements in agriculture. However, there is a tradeoff between the quantity of water used in agriculture and the quality of return flow. Where yields are low due to limited nitrogen (N) and water supply, water productivity can be enhanced through higher fertilizer applications and improved water management. This limits the amount of additional water needed for increased food demand, thus leaving more water for environmental requirements. But it also increases the amount of nitrate (NO3–N) leaching, thus adversely affecting the water quality of return flows. This paper quantifies the tradeoff between enhanced water productivity and NO3–N leaching and shows the importance of the right management of water and N applications. Using the Decision Support System for Agro-technology Transfer (DSSAT) crop model, several scenarios combining different water and N application regimes are examined for maize (Zea mays L.) in Gainesville, FL, USA. Without adequate water, nitrogen use efficiency (NUE) remains low, resulting in substantial NO3–N leaching. Too much water leads to excessive NO3–N leaching and lower water productivity. The lack of N is a cause of low water productivity but too much of it leads to lower NUE and higher losses. The paper concludes that increased NO3–N leaching is an inevitable by-product of increased water productivity, but its adverse impacts can greatly be reduced by better management of water and N application. The paper briefly shows that leaching can be reduced and water productivity increased by split application of N-fertilizer. This implies that improved water and nutrient management at field- and scheme-level is a prerequisite to limit adverse impacts of agriculture on ecosystems, now and especially in the future.
3 Nangia, Vinay; Gowda, P. H.; Mulla, D. J.; Sands, G. R. 2008. Water quality modeling of fertilizer management impacts on nitrate losses in tile drains at the field scale. Journal of Environmental Quality, 37(2):296-307.
Water quality ; Simulation models ; Calibration ; Fertilizer application ; Nitrogen fertilizers ; Soyabeans ; Maize ; Subsurface drainage / USA / Gulf of Mexico / Mississippi River / Minnesota
(Location: IWMI HQ Call no: IWMI 631.8 G430 NAN Record No: H040829)
Nitrate losses from subsurface tile drained row cropland in the Upper Midwest U.S. contribute to hypoxia in the Gulf of Mexico. Strategies are needed to reduce nitrate losses to the Mississippi River. This paper evaluates the effect of fertilizer rate and timing on nitrate losses in two (East and West) commercial row crop fields located in south-central Minnesota. The Agricultural Drainage and Pesticide Transport (ADAPT) model was calibrated and validated for monthly subsurface tile drain flow and nitrate losses for a period of 1999–2003. Good agreement was found between observed and predicted tile drain flow and nitrate losses during the calibration period, with Nash-Sutcliff e modeling efficiencies of 0.75 and 0.56, respectively. Better agreements were observed for the validation period. The calibrated model was then used to evaluate the effects of rate and timing of fertilizer application on nitrate losses with a 50-yr climatic record (1954–2003). Significant reductions in nitrate losses were predicted by reducing fertilizer application rates and changing timing. A 13% reduction in nitrate losses was predicted when fall fertilizer application rate was reduced from 180 to 123 kg/ha. A further 9% reduction in nitrate losses can be achieved when switching from fall to spring application. Larger reductions in nitrate losses would require changes in fertilizer rate and timing, as well as other practices such as changing tile drain spacings and/or depths, fall cover cropping, or conversion of crop land to pasture.
4 Bossio, Deborah; Noble, Andrew; Molden, David; Nangia, Vinay. 2008. Land degradation and water productivity in agricultural landscapes. In Bossio, Deborah; Geheb, Kim (Eds.). Conserving land, protecting water. Wallingford, UK: CABI; Colombo, Sri Lanka: International Water Management Institute (IWMI); Colombo, Sri Lanka: CGIAR Challenge Program on Water & Food. pp.20-32. (Comprehensive Assessment of Water Management in Agriculture Series 6)
Land degradation ; Water scarcity ; Water productivity ; Land management ; Crop production ; Evapotranspiration
(Location: IWMI HQ Call no: IWMI 631.7 G000 BOS Record No: H041591)
5 Jiantao, D.; Wenqing, H.; Nangia, Vinay; Changrong, Y.; Ahmad, Mobin-ud-Din; Shuang, L.; Qin, L. 2008. Effects of conservation tillage on soil water content in northern arid regions of China. In Chinese. Transactions of the Chinese Society of Agricultural Engineering, 24(11):25-29.
Conservation tillage ; Soil water ; Water balance ; Models ; Water use efficiency ; Water productivity / China
(Location: IWMI HQ Call no: IWMI 631.451 G592 JIA Record No: H041714)
Soil water content is the key factor that affect the agriculture production in northern arid regions of China. It is helpful to select proper tillage methods and improve water productivity based on the study of soil water content changing. Soil water content, water balance and water use efficiency were simulated and checked used the DSSAT model based on two-year field experiment. The results show that in dry year the soil water content of conservation tillage is higher than the conventional tillage, RMSE is 0.025-0.063. In dry year, and the largest decrease of soil water storage is conventional tillage (144.6 mm), and the same in normal year (46.1 mm). Water use efficiency in dry year is 1.52-1.78 kg/m3, the largest is no tillage with residue cover treatment, in the normal year is 1.70-1.71 kg/m3. The differences between different treatments are not obvious. The results provide theoretical foundation for the research of effects of conservation tillage on soil water in the field.
6 Lu, X.; Nangia, Vinay; Mu, X.; Wang, F.; Sui, Y.; Gao, P.; Yao, Y. 2009. Field-scale simulation of winter-wheat leaf area index, soil moisture and water-use efficiency in west Henan, China. Journal of Environmental Hydrology, 17(10):1-11.
Wheat ; Plant growth ; Simulation models ; Tillage ; Soil water ; Water balance ; Water use efficiency / China / West Henan region / Mengjin county / Songzhuang village
(Location: IWMI HQ Call no: IWMI 633.11 G592 LU Record No: H042056)
(0.14 MB)
7 Nangia, Vinay; Ahmad, Mobin-ud-Din; Du, J.; Changrong, Y.; Hoogenboom, G.; Xurong, M.; Wenqing, H.; Shuang, L.; Qin, L. 2009. Modeling the effects of conservation agriculture on land and water productivity of rainfed maize in the Yellow River Basin, China. In Humphreys, E.; Bayot, R. S. (Eds.). Increasing the productivity and sustainability of rainfed cropping systems of poor smallholder farmers: proceedings of the CGIAR Challenge Program on Water and Food, International Workshop on Rainfed Cropping Systems, Tamale, Ghana, 22-25 September 2008. Colombo, Sri Lanka: CGIAR Challenge Program on Water and Food. pp.147-166.
Tillage ; Simulation models ; Water productivity ; Soil water ; Water balance ; Maize ; Crop yield / China / Yellow River Basin
(Location: IWMI HQ Call no: 631 G000 HUM Record No: H042440)
http://www.dfid.gov.uk/r4d/PDF/Outputs/WaterfoodCP/CPWF_Proceedings_Rainfed_Workshop%5B1%5D.pdf
https://vlibrary.iwmi.org/pdf/H042440.pdf
https://vlibrary.iwmi.org/pdf/H042440.pdf
(0.47 MB) (8.92MB)
In the dryland regions of North China, water is the limiting factor for rainfed crop production. Conservation agriculture (featuring reduced or zero tillage, mulching, crop rotations and cover crops) has been proposed to improve soil and water conservation and enhance yields in these areas. Conservation agriculture systems typically result in increased crop water availability and agro-ecosystem productivity, and reduced soil erosion. To evaluate the potential of conservation agriculture to improve soil water balance and agricultural productivity, the DSSAT crop model was calibrated using the data of a field experiment in Shouyang County in the semi-arid northeastern part of the Yellow River Basin. The average annual precipitation at the site is 472 mm, 75% of which falls during the growing season. The site had a maizefallow-maize rotation. We used data from two crop seasons (2005 and 2006) and four treatments for calibration and analysis. The treatments were: conventional tillage (CT), no-till with straw mulching (NTSM), all-straw incorporated (ASRT) and one-third residue left on the surface with no-till (RRT). The calibration results gave satisfactory agreement between field observed and model predicted values for crop yield for all treatments except RRT, and for soil water content of different layers in the 150cm soil profile for all treatments. The difference between observed and predicted values was in the range of 3-25% for maize yield and RMSE was in the range of 0.03-0.06cm3/cm3 for soil water content measured periodically each cropping season. While these results are encouraging, more rigorous calibration and independent model evaluation are warranted prior to making recommendations based on model simulations. Medium-term simulations (1995-2004) were conducted for three of the treatments using the calibrated model. The NTSM and ASRT treatments had similar or higher yields (by up to 36%), higher crop water productivity by up to 28% and reduced runoff of up to 93% or 43 mm compared to CT.
8 Nangia, Vinay; Turral, Hugh; Molden, David. 2008. Increasing water productivity with improved N fertilizer management. Irrigation and Drainage Systems, 22:193-207. [doi: https://doi.org/10.1007/s10795-008-9051-9]
(Location: IWMI HQ Call no: PER Record No: H043214)
There is continuing debate about the role of water productivity and the potential to increase it in response to significantly increased water demand to meet the future needs for food—estimated to be roughly double that of today by 2050. The debate centers round the relative potential benefits of enhancing rainfed agriculture, improving irrigation and expanding areas of both. All expansion and intensification options will require significantly more water to be used, often in places where the ecosystem impacts of agriculture are already severe. Improvement in water productivity can result from improving the provision and management of the other factor inputs of crop production. There is considerable debate on the ability of other inputs—typically nitrogen—to substitute for water. This paper describes a set of simulations undertaken with well calibrated maize (Zea mays L.) crop model in Decision Support System for Agro-technology Transfer (DSSAT). The simulations investigate the response to nitrogen under rainfed conditions in Florida, and show that neither the transpiration ratio nor the harvest index are constant in practice, and that fertilizer use can enhance water productivity, even in quite high yield conditions and that the transpiration ratio can be increased by N fertilizer application at low levels of crop water use.
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