Drought and Nutrient Management

Adapted by Dr. Deanne Meyer, UCCE Waste Management Specialist

Here we are again after yet another dry year.  A few important tips to remember when dealing with nutrient management this spring.  You’ll want to work with your CCA (certified crop adviser) to be sure the nutrient budget is up to date for your current cropping pattern. You’ll especially want to be sure there is sufficient water for the acres you plant.  Keep in mind that almost all dairies under the General Order are also in the representative groundwater monitoring program.  To remain in the program, nutrients need to be applied to meet identified needs (as per your budgets).

As the Regional Board staff are out doing inspections they’ll focus on budgets and manure applications to fields where crops are growing.  As a refresher …Your Nutrient Budget identifies for each crop in each field how much Nitrogen (N) to apply, when to apply, source of N (manure, fertilizer, irrigation water), maximum period of time anticipated between application events (storage needs), method of manure and process wastewater application, and review of soil and crop tissue analyses every 5 years by an agronomist if phosphorus and/or potassium applications exceed crop removals.  Budgets also reflect estimated crop yield.  BE SURE TO EVALUATE YOUR NUTRIENT BUDGET AND MODIFY AS NECESSARY.

MODIFY YOUR NUTRIENT BUDGET (GET a Certified Crop Adviser Signature) if you change crops grown (including fallowing land), have a change in yield expectations, or change your source of irrigation water.  Remember, the Nutrient Budgets are meant to be modified regularly.  If your budget was signed in 2010 and it hasn’t been updated, odds are pretty good that it may not represent your current cropping practices and you could have a challenge during a Regional Board inspection.  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?  Current 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.  Keep in mind the Regional Board is contemplating if dairies who over apply manure should install their own groundwater monitoring wells (and not be allowed to participate in the representative program).

Modify manure applications.  Evaluate your Nutrient Budgets to identify if you should modify manure applications.  If you estimate a change in crop N uptake/removal, have nitrate available in groundwater irrigation sources, or fallow land, manure applications will need to be adjusted in order to accommodate changes in anticipated applications or yields. 

If you are manure rich and planted acreage poor … manifest as much solid manure off-site as possible.  Be sure you 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 re-evaluate and apply liquid manure and irrigation water accordingly.

Link to PDF Version: Drought and Nutrient Management