By Deanne Meyer, Ph.D., Livestock Waste Management Specialist, UC Davis, Department of Animal Science, UC ANR
Here we are again, DRY. Let’s dust off key nutrient management tips during drought. Work with your certified crop adviser (CCA) to be sure the Nutrient Budgets are up-to-date for your current cropping pattern. When Regional Water Quality Control Board staff are out doing inspections, they will focus on budgets and manure applications to fields where crops are growing. Nutrient Budgets identify for each crop, in each field:
☐ How much Nitrogen (N) to apply;
☐ When to apply;
☐ The source of N (manure, fertilizer, irrigation water);
☐ The maximum period of time anticipated between application events (storage needs);
☐ The method of manure and process wastewater application;
☐ Estimated crop yield; and
☐ A review of soil and crop tissue analyses every 5 years by an agronomist if phosphorus and/or potassium applications exceed crop removals.
Modify Manure Applications
Evaluate your Nutrient Budgets to identify if you should modify manure applications. Modify manure applications as needed based on estimated change in crop N uptake/removal, nitrate concentration in groundwater and fallow land. If you are manure rich and planted acreage poor, sample and manifest as much solid manure off-site as possible. Distribute liquid manure according to your nutrient budget. Carefully evaluate where you will get your greatest yields (especially if you have some poorer performing fields) and apply liquid manure and irrigation water accordingly.
Modify Your Nutrient Budget
(Get a CCA Signature) if you change which crops you grow (including fallowing land), have a change in yield expectations, or change your source of irrigation water. Remember, Nutrient Budgets are a living document. If your budget was signed in 2010, it may not represent your current cropping practices. Current Budgets make inspections run smoother. Inspectors are looking very closely at Nutrient Budgets when they inspect dairies. What crop should be in the ground? When was it planted? What is the expected date for harvest? How much nitrogen has been applied? Previous violation notices to dairy operators who applied manure without a growing crop have included the need to remove the manure from the field and potential fines.
Almost all Central Valley dairies are also in the representative groundwater monitoring program. To remain in the program, nutrient application must be consistent with Budgets.
On a separate note, sample forages for nitrate from all fields where yields were markedly reduced. Discuss these results with your dairy nutritionist.