How Much Nitrogen Shall I Add?

More often than not, it is nitrogen that limits plant’s size and vigor. Most labs don’t test for nitrogen – test results are variable, and the situation in the field changes often. It’s up to the grower to supply the right amount of nitrogen at the right time. It is extremely important to provide sufficient nitrogen but not too much.

Nitrogen requirements vary with the crop, the crop maturity, the quality and quantity of the organic matter present in the soil, and other factors.

OrganiCalc uses 100 lbs/acre of N at the default target, however this may be changed by entering a different value in the box. Another way to estimate an appropriate N target is to look at the quantity of organic matter. This method does not take into account the quality of the organic matter or amount of biological activity, however it may be useful as a starting point.

OM% less than 3%: 200 lbs/ac
OM% between 3% and 5%: 100 lbs/ac
OM% between 5% and 8%: 50 lbs/ac
OM% more than 8%: 0 lbs/ac

If you are going to incorporate a leguminous cover crop, use less (or no) additional nitrogen.

If you have an extremely biologically active soil with lots of earthworms, use less (or no) additional nitrogen.

We apply up to 300 lbs of N as feathermeal when preparing our low (3%) organic matter soil. Feathermeal is extremely slow release; applying 300 lbs/ac is like applying 200 lbs/ac of any other N source. In addition, we apply liquid fish (5-1-1) to seedlings to help get them going. We also use high P liquid fish later in the growing season.

Would you like a more detailed discussion about Nitrogen?