29 Apr Sorghum Fertility
We recently discussed sorghum seeding rates, which gain a lot of attention at times. Sorghum soil fertility decisions can have a bigger impact and is one area that sorghum overall needs to improve. Making fertilizer decisions for sorghum is pretty straight forward and there are a lot of good recommendation tools to choose from.
If you want sorghum fertilizer recommendation tools that considers the complexity of the N, P, and K cycles in your soil, Kansas State Agronomy has the tool for you. Figure 1 contains the N recommendation equation from Soil Test Interpretations and Fertilizer Recommendations (MF-2685) from KSU Agronomy.
Figure 1. Grain Sorghum nitrogen recommendation model from Kansas State Agronomy Dept.
This equation allows for adjustments for irrigation water N and previous annual or perennial crop impacts on N status in a given field. The P and K models have adjustments for yield goal and crop removal and overall P and K management strategies. There are also models for secondary and micronutrients like chloride, zinc, boron, and sulfur. They also have models for sorghum silage and forages. If you are not familiar with this publication, I highly recommend it. It can be found at:
If you prefer more traditional and easier to apply fertilizer recommendation models for grain and forage sorghum Oklahoma State has the nutrient recommendation system for you. OSU Soil Test Interpretations (PSS-2225) has tables for each crop and nutrient you are interested in. Figure 2 has the sorghum nitrogen, phosphorous, and potassium tables.
This publication also has recommendations for secondary and micronutrients like chloride, zinc, boron, and sulfur. They also have recommendations for sorghum silage and forages. If you are not familiar with this publication, I highly recommend it. It can be found at: https://extension.okstate.edu/fact-sheets/osu-soil-test-interpretations.html#notes-for-nitrogen-n-interpretations
Proper sorghum fertilizer decisions are as important to achieving high yields as selecting the right hybrid, getting it planted at the right time and using the correct seeding rate. You have to get all of these decisions right to make sure that your sorghum yield potential is maximized and all that is left is what mother nature gives you for rain and sunshine.