abstract rice is most important agricultural crop of guilan province sensibility to salinity and alkalinity of water and soil. in recent years, using of toxicants and fertilizers in farmlands, constructing several dams upstream, entering agricultural, homemade and industrial sewage in to a river, and drought have decreased gradually discharge of river and increased salinity of sefidrud river as...

Rice is an essential crop in Iran that is grown mostly in areas where depth to groundwater is low. Root growth and water uptake of rice under shallow groundwater has not been thoroughly studied. This experiment was conducted to determine the lowland rice (cv. Ghasrodashti) root distribution above shallow groundwater in relation to deficit irrigation and groundwater depth in cylindrical gre...

abstract optimal management of water and nutrient could consider as effective on farm method to reduce pollution because agriculture is none point pollution. in this research, an optimal model was presented to reduce nitrate loss in furrow fertigation. the optimal model contains four simulation models for predicting runoff, deep percolation, nitrate concentration in runoff and nitrate concentra...

abstract in order to study the effects of different irrigation management on water productivity of local, improved and hybrid rice varieties an experiment was carried out on a split plot design with 3 replications. the varieties were splited on 5 irrigation methods (i.e. full irrigation, awd, 5, 8 and 11 day irrigation interval) at rice research institute of iran, rasht during cropping season o...

Purpose Water management affects the bioavailability of cadmium (Cd) and arsenic (As) in the soil and hence their accumulation in rice grains and grain yields. However, Cd and As show opposite responses to soil water content, but information, particularly on irrigation, is missing on a field scale. The purpose of the present study was therefore to find a water management regime that can lower a...

Water control is mainly one of the key factors that can affect nitrous oxide (N2O) emissions from soils. This study was undertaken to determine the effect of intermittent drainage compared to continuous flooding (conventional water regime) on N2O emission to global warming potential (GWP) with NPK (standard cultivation practice), NPK+Straw, and PK fertilizations. Nitrous oxide emission rates we...

Simulating irrigation systems by accounting for various water loss rates is necessary while modeling the hydrology of cultivated canal-irrigated watersheds. The existing approaches to modeling canal irrigation use situation-specific optimization procedures. In addition, they are focused on a water management perspective rather than a hydrologic perspective. In this study, an approach is develop...

this paper presents a relatively new management model for the optimal design and operation of irrigation water pumping systems. the model makes use of the newly introduced particle swarm optimization algorithm. a two step optimization model is developed and solved with the particle swarm optimization method. the model first carries out an exhaustive enumeration search for all feasible sets of p...