A modified Mitscherlich equation for rained crop production in semi-arid areas: 2. Case study of cereals in Syria

Abstract

In a companion paper, a theoretical framework for the application of the Mitscherlich equation to describe nutrient response for rainfed crop production is presented. Water-limited potential, or maximum, yield is assumed to be a linearly increasing function of seasonal rainfall. In addition, the quantity of nutrients required by a crop to achieve water-limited potential yield and the nutrient availability are also expressed as functions of seasonal rainfall. This rainfall-dependent Mitscherlich equation is evaluated using data from agronomic (nitrogen x phosphorus) experiments conducted under rainfed conditions in the semi-arid region of Syria. The analysis showed that rainfall explained most of the variation in yield between locations and seasons, but that the moisture-dependent nutrient part of the Mitscherlich equation explained a small but significant part of the yield variation as well. The model discussed in this paper appears to provide a framework for a Mitscherlich-type approach to describing crop response to nutrient availability c.q. fertilizer application under rainfed conditions in the semi-arid regions.