Nutrient Management Research Database

http://ucanr.edu/sites/Nutrient_Management_Solutions/files/218294.pdf

Delayed addition of manure water holds promise as a means of improving nutrient application uniformity and of applying less nitrogen during an irrigation while still using existing high flow rate manure water pumps and pipelines. Two disadvantages of delaying manure water applications are that there is a delay once manure water pumps are turned on until manure water reaches the irrigated field. For the field evaluated in this study, that delay was approximately 20 minutes. Secondly, it is quite common for dairies to be irrigating multiple fields at the same time, often at different locations on the dairy and utilizing complex piping systems, to deliver the water. This makes delayed manure water additions, as well as any form of manure water nutrient management, a complex and sophisticated task.

A field project was implemented on a Tulare county dairy during the summers of 2001 and 2002 to assess methods for improving irrigation and nutrient management of flood irrigation systems that apply manure water.  The the effect of timing of manure water additions to irrigation water on application uniformity was evaluated using a sulfur fertilizer tracer that could be tracked visually.  Water samples collected frequently at multiple locations along the furrow, RBC flumes were used to monitor flow rate, and advance/recession measurements were also gathered.  

The sulfur fertilizer tracer tests showed that manure water additions could be added to clean irrigation water after the water had advanced 900 ft down the 1200-foot long field. Irrigation uniformity was 64%. Delaying the manure water application until irrigation water had advanced 900 feet along the furrow led to a manure water application uniformity of 69%, and reduced average N applications from 242lbs/acre to 86lbs/acre. Delaying manure water additions to the irrigation water led to more uniform nutrient applications and a potential to reduce nutrient applications as well.