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.