Determining Optimum Nitrogen Rates for Irrigated Timothy Hay for Export

Background

I am located in the center of irrigated timothy production for Washington State. Timothy hay is our largest grass hay commodity and we export it to Japan and other countries. We can produce 10 ton per acre in cuttings but most farmers use two cuttings and receive around 5 - 7 tons/acre. Very little work has been done on determining optimum nitrogen rates for this commodity. Yet we grow this irrigated crop on an estimated 86,700 acres in Washington, 113,300 acres in Oregon, and 135,900 in California without adequate research to know what N rate to use or techniques to evaluate in-season nitrogen. The value of this crop in the three states approaches $400 million annually. In the winter of 2013, because of this need, my colleagues and I wrote and I received grants from WSU BIOAg as well as Washington State Hay Growers Association to study nitrogen rates on timothy and teff as well as the intercropping of both species. These grants have allowed me to study the establishment year of timothy and one year of data at two locations for the second year of timothy and produce information on nitrogen leaf concentration as well as using a SPAD meter for in season assessment.

Figure 1. First cut yield per acre Prosser in 2013 and 2014 and Othello in 2014.

Figure 2. Relationship between March nitrogen rate applied as Agrotain and harvest protein of hay.

It is important to see if results from second year, timothy being a perennial crop, correspond to the first year or is different. Again we are interested in soil fertility recommendations, leaf tissue, and SPAD meter information for in-season adjustments as necessary. We are also following quality for each cutting as an assessment of nitrogen rate applied.

The information you would receive at two locations in 2015 include: SPAD meter readings and tissue samples at six times per year, soil samples for nitrate and ammonium at first and second foot beginning, and end of the year and first foot only after first and second cutting. Harvest quality of timothy by NIRS would also be included which contains many parameters including protein, NDF, ADF, etc.