Interactive effects of soil salinity, fertility, and irrigation on field corn

Abstract

A line-source field experiment was conducted to study the interactive effects of four levels of soil salinity, five rates of applied nitrogen fertilizer and six levels of irrigation on the production of field corn (Zea mays L.). In general, increased levels of soil salinity and decreased irrigation reduced grain and stover (stems and other above-grand dry matter) yields. Increased quantities of irrigation, presumably through maintenance of high (less negative) total soil water potential, were effective in decreasing the effect of salinity, and as a result improved yield. The highest salinity level (9.6 mmho/cm) resulted in dry matter yield reductions of 41 and 93 percent of the maximum observed yield at the highest (479 mm) and lowest (210 mm) irrigation levels respectively, averaged over all fertility levels. Under the same conditions grain yield declined by 48 and 96 percent. Yield was not improved as a result of applying nitrogen. Main effects on yield of salinity (1% level), water (1% level) and nitrogen (5% level) were found. Interactive effects upon yield were demonstrated for salinity X nitrogen (1% level) and salinity X water (1% level) combinations. Nitrogen content of stover and grain rose with increased levels of soil salinity and nitrogen, and declined with increased irrigation. A salinity X nitrogen interaction effect was demonstrated for nitrogen content of the grain, and a salinity X water effect demonstrated for stover. Multiple regression equations for stover and grain yields as functions of salinity, fertility and irrigation were developed (R2 = 0.88 and 0.85 respectively).