Correcting Iron Deficiency in Corn with Seed Row–Applied Iron Sulfate

Corn (Zea mays L.) grown on calcareous, high-pH soils is susceptible to Fe deficiency, which can reduce grain yield by as much as 20%. The objective of this study was to evaluate several treatments of FeSO4 that could be used with precision-farming technologies to alleviate Fe deficiency in irrigated corn. Three sites in 1999 and four in 2000 were selected (based on a history of Fe deficiency) for small-plot (3 by 12.2 m) studies in western Kansas. In 1999, five treatments, including four rates of FeSO4·H2O (0–81 kg ha−1 product) applied in the seed row and one foliar treatment (chelated Fe), were evaluated. In 2000, two additional treatments, CaSO4·2H2O (85 kg ha−1 product) and liquid FeSO4·7H2O (91 kg ha−1 product) applied in the seed row, were included. Grain yield increased linearly with increasing rates of FeSO4·H2O at four of seven site-years, increasing 0.02 Mg ha−1 for each kilogram per hectare of FeSO4·H2O applied. Based on yield responses observed in this study, 81 kg ha−1 FeSO4·H2O was the most consistent treatment for correcting Fe deficiency in corn. If the average yield response obtained in this study can be achieved on 15% of an individual cornfield, the expected return would be $3.00 ha−1 for the entire field. Current precision-farming technologies allow application of FeSO4·H2O only to areas susceptible to Fe deficiency. Employing these technologies provides a practical solution to the spatial heterogeneity of Fe deficiency in irrigated corn and increases the probability of crop response to the fertilizer application.