Correction of lime‐induced chlorosis in soybeans in a glasshouse with sulfur AMD an acidifying iron compound

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Abstract
PI54619–5–1 soybeans were grown for 28 days in calcareous Hacienda loam soil in which small quantities of amendments to correct iron chlorosis were placed just under the seed. The amendments used were combinations of sulfur and a waste iron product containing a crystalline form of sulfuric acid. Mixtures of sulfur and the acidifying material produced better prevention of the lime‐induced chlorosis than did either product alone. Suggested is that the sulfur‐oxidizing bacteria function more efficiently when calcareous soil is acidified than in the original soil. Host effective results were obtained with rates equivalent to 370 kg/ha for the acid iron waste product, 185 kg/ha for 25%‐75%, 50%‐50%, and 75%‐25% mixtures of both products while 185 kg/ha of elemental sulfur gave little response. Rates equivalent to 93 kg/ha gave 31%, 60%, 65%, 76% and 94% of maximum response respectively for all sulfur, for all acid iron waste, for 25%‐75%, 50%‐50% and 75%‐25% of the acid iron waste‐sulfur mixtures. Control was 24% of maximum response. Iron uptake per plant in leaves was highly correlated with yield (r = +0.97), but iron concentration in leaves was not. The correlation between leaf concentration and yield was ‐0.93 for P, ‐0.77 for K, ‐0.83 for Cu, ‐0.79 for Al, ‐0.60 for Si, ‐0.55 for Ca, and ‐0.54 for Zn. The P and K status are indicative of lime‐induced chlorosis.