Citadels

Book:  Improving Drought Tolerance

William “Crop Doc” McKibben is the author of The Art of Balancing Soil Nutrition, available from Acres U.S.A.   For more information call 800-355-5313, visit www.acresusa.com or visit the Acres USA national office bookstore at:  4031-B Guadalupe St., Austin  TX  78751

Selected quotes from the June 2013 ACRES U.S.A. magazine article on page 30

Calcium

“Balancing the standard soil test using the Base Cation Saturation Ratio (BCSR) will help to minimize compaction on the soil chemistry side.  Many universities have had a hard time accepting this idea. … The key to withstanding droughty conditions is having a big, deep root mass.   … I personally feel that you need to look at the soil paste analysis to see if there is enough calcium in the soil solution to provide roots with adequate calcium at the growing points.  Calcium is critical to cell wall strength and helping to push the root cap through the soil profile.  In the area behind the root cap and the area of cell differentiation, calcium is absorbed into the cell wall for strength, and as the cells expand by filling with water the root cap is pushed through the soil.  The lack of adequate calcium will cause the cells to buckle when they encounter resistance.  Ultimately, this reduces root mass and the plant’s ability to withstand droughty conditions.  This also hinders roots from picking up other nutrients such as phosphorous and potassium, which are critical in drought protection.

…  The best crop yields seem to come from soils that have around 30 ppm of calcium in the paste analysis. … Liming low pH soils with the correct ime and using small amounts of lime generally in the 2,000-3,000 pound rate can be the cheapest way to improve calcium solubility.

Phosphorous

…  Phosphorous is critical for root development among other things.  It controls the energy in the plant and can move upward or downward in the plant depending upon need.

Potassium

…  One of its more important jobs in the plant is to regulate water usage.  …  As potassium becomes deficient in the plant, the stomata fail to open and close properly, causing the plant to lose water.  Plants deficient in potassium require more water to produce the same yield as those with adequate levels.

Summary:

… I have mentioned three nutrients – calcium, phosphorus, and potassium – which significantly impact plants root development and water utilization.  This is not to say that the other nutrients should not be taken seriously.  Boron and zinc deficiencies impact calcium and phosphorus uptake respectively.