Sorghum Yield and Soil Analysis from Sludge‐Amended Calcareous Iron‐Deficient Soil1

Abstract

AbstractSorghum [Sorghum bicolor (L.) Moench] often becomes iron deficient when grown on calcareous iron‐deficient soils. Two experimental sites were selected with a history of severe iron chlorosis on sorghum to the point of plant death before maturity. Correcton of the Holloman soil (fine‐loamy, gypsic, thermic, shallow Typic Torriorthent) has not been practical with available treatments. A 5‐yr experiment consisting of sludge (89.6 Mg/ha) and dairy manure (89.6 Mg/ha), each applied the first year only, plus a fertilized check with N and P applied annually was conducted on one site. A 3‐yr experiment comparing two rates (33.6 and 67.2 Mg/ha) of sludge applied only the first year plus a fertilized check with N and P applied annually was conducted on the second site. Sludge was applied to half of each sludge plot the last year of each experiment to evaluate residual effects of sludge applied at the beginning. In both experiments, grain yields were low on the fertilized check plots and on the manure treatments after the first year. Sludge improved yields and soil test Fe levels, and corrected sorghum chlorosis throughout both experiments. For at least 5 yr following application, sludge also increased soil test levels of Zn and P.