3rd UF Water Institute Symposium Abstract

Submitter's Name	Dakshina Murthy Kadiyala
Session Name	Posters - Water Conservation and Use 2
Category	Water Conservation and Use
Poster Number	81
Author(s)	Dakshina Murthy Kadiyala,  Soil and Water Science Department, University of Florida (Presenting Author)
	James W Jones,  Department of Agricultural and Biological Engineering, University of Florida
	Rao Mylavarapu, Soil and Water Science Department, University of Florida
	Li Yuncong, Soil and Water Science Department, University of Florida
	Devender Reddy, Water Technology Center, ANGR Agricultural University, India
	Study of Spatial Water Requirement of Rice under Various Crop Establishment Methods Using GIS and Crop Models
	Traditional rice transplanting method of cultivation faces severe yield limitations due to frequent monsoon rain failures, which result in water stress during critical periods of rice growth. To meet the water demands of traditional flooded rice crops, farmers need to pump more water from underground aquifers. This continuous pumping causes depletion of the underground water and creates serious ecological and environmental consequences. Crop models have been utilized for yield predictions, irrigation planning, irrigation optimization, comparing various scenarios and strategies, analyzing yield trends over time, etc. However, these models need to be applied at scales that are economically useful for analysis of various alternate rice management strategies on water savings across the watershed or the region. Linking crop models with Geographical Information System (GIS) has demonstrated a strong feasibility of crop modeling applications at a spatial scale. In the present study, spatial analysis of long- term simulations were carried out with DSSAT spatial analysis tool linked with GIS to estimate irrigation requirements and nitrate leaching under alternate rice establishment methods in the Wargal watershed, Andhra Pradesh, India. Rice yields were compared among three management scenarios: rainfed, aerobic and flooded. Grain yield, seasonal water balance components, nitrate leaching, water use efficiency and irrigation use efficiency were calculated, visualized and mapped with GIS. The rice productivity increased by 22% and 27% under aerobic and flooded management compared to rainfed rice. The adoption of new water efficient aerobic rice cultivation in the watershed resulted in 36% water saving with a relatively small yield reduction of 4%, thus increasing the water productivity to 0.77 g kg-1 in aerobic compared to 0.56 g kg-1 in flooded rice. The aerobic rice method reduced the overall water pumping to 88 h ha-1 during rice crop season compared to 299 h ha-1 with flooded rice cultivation, resulting in 71% energy savings.