Guest Author: Skylar Gibson
Calcium carbonate (Ag-Lime) has been used as a liming agent in soil to buffer pH for decades with little regard to the quality of Ag-Lime they were using and the other benefits Ag-Lime can provide. Ag-Lime varies in composition from 34% calcium to 26% calcium with magnesium levels varying from 3% to 10%. A Hi-Cal lime, a lime with 34% calcium and 3% magnesium is the recommended lime to use because of the 10:1 ratio between the calcium and magnesium. The granular consistency is also important and normally overlooked. A fine granular consistency where 60% of the product passes through a 100 mesh screen is recommended. The fine granular consistency increases calcium availability and helps with solubilization in the soil.
Calcium Sulfate (Gypsum) has come to the front lines nationally not only as a fertilizer but the most cost effective source of calcium and sulfur. Gypsum has an analysis of 24% calcium and 16% sulfur that equates to 320lbs of available sulfur per ton of gypsum. Gypsum is a fine granular consistency and more soluble than Ag-Lime thus making the 480lbs of calcium you get per ton available more quickly in the soil.
The calcium to magnesium ratio in your soil has a direct influence on the overall productivity. Soils with low calcium to magnesium ratios tend to be harder when dry with less aeration. These soils typically get slicker when wet and crack when dry. Hardpans are generally seen in these soils because of lack of calcium and plowing to the same depth year after year. The optimum calcium to magnesium ratio is 8:1. As your soil’s calcium to magnesium ratios improve the soil can breathe better and microbial life can thrive. Calcium to magnesium ratios directly impact root penetration. As your soil becomes more saturated with calcium roots are able to penetrate deeper into the soil when rainfall is scarce.
Ag-Lime and gypsum are both great sources to help improve your calcium to magnesium ratios. Ag-Lime would be recommended to improve this ratio if the pH of the soil is imbalanced because Ag-Lime buffers at an optimal level for plant growth between 6.8 and 7.2. Gypsum would be a better source to affect your calcium to magnesium ratios if your pH was at optimal range and your crops show sulfur deficiency. If your soil has neither pH imbalance nor sulfur deficiency the most economical source would vary by your location and availability of product.Read More About: ag lime, calcium sulfate, gypsum, pH, soil