Crop‐Water Production Function Model for Saline Irrigation Waters

Abstract

The relationship between crop yield and seasonal amount of applied water (crop‐water production function) is required to determine optimum irrigation management. A model is developed for the computation of crop‐water production functions with saline irrigation waters. The model combines three relationships: yield and evapotranspiration, yield and average root zone salinity, and average root zone salinity and leaching fraction. The model allows plant growth adjustment, and therefore evapotranspiration adjustment, to root zone salinity. Crop‐water production functions were computed for tall fescue (Festuca elatior arundinacea L.) for various levels of salinity in the irrigation water. A comparison was made between calculated and published experimentally measured values of leaching fractions and yields of tall fescue grown under conditions of various irrigation water salinities, water application quantities and applied water frequencies. Calculated and measured yields were in good agreement considering the usual degree of variability of field data. Agreement between calculated and measured leaching fractions was not as good as for yields.

Evapotranspiração e produção do melão Gália irrigado com água de diferentes salinidades e adubação nitrogenada

“…Vários pesquisadores têm tentado desenvolver uma função de produção para as culturas em relação à água de irrigação salina (Letey et al, 1985;Letey & Dinar, 1986;Bresler, 1987). Esses modelos combinam relações entre rendimentos e evapotranspiração, entre rendimento e salinidade na zona radicular e entre salinidade na zona radicular e a fração de lixiviação.…”

The Impact of Seawater Salinity on Evapotranspiration and Plant Growth Under Different Meteorological Conditions

“…It was reported that increased evaporation from the soil surface can counteract the reductions in K c caused by high EC e of the root zone (FAO, 1998). Letey et al (1985) and Shalhevet (1994) reported that the effects of soil salinity and water stress were interactive to crop evapotranspiration.…”

“…Because of this, under saline conditions, the K s reducing factor should only be applied with the dual K c approach (FAO, 1998). In reviewed articles on impacts of salinity on crop production, Letey et al (1985) and Shalhevet (1994) concluded that the effect of soil salinity and water stress are generally additive in their impacts on crop evapotranspiration. Therefore, the same yield-ET functions may hold for both water shortage induced stress and for salinity induced stress.…”

Sustainable conjunctive water management in irrigated agriculture: Model formulation and application to the Yaqui Valley, Mexico

“…model for soil salinization as a function of amount and salinity of the irrigation water [Letey et al, 1985],…”

“…Assumptions and limitations of the model were discussed by Letey et al [1985]. A disadvantage of the model is that it requires an iterative solution, because of the mutual dependence of RY, YD, LF, EC e , and DP.…”