2004 - Accurate fertilizer P rates for ryegrass calibrated for different soil-P extractants
2003 - Accurate Fertilizer P Rates for Ryegrass Calibrated for Different Soil P Extractants
2002 - Accurate Fertilizer Phosphorus Rates for Ryegrass Calibration for
Different Soil Phosphorus Extractants
Accurate Fertilizer Phosphorus Rates for Ryegrass Calibrated for Different Soil Phosphorus Extractants, 2003
Annual ryegrass is an important high quality cool season forage crop with excellent yield potential. Earlier (1996 to 1999) research supported by PPI and FAR demonstrated that high yield ryegrass production in southwest Texas required substantial levels of nitrogen (N) and phosphorus (P) fertilizer. To further evaluate ryegrass fertility in central Texas, the current study was initiated in the fall of 2001 near Stephenville. The soil type and environment in the current study differ substantially from the earlier work. The objectives of this study are to: 1) evaluate annual ryegrass yield response to N and P fertilizer, and 2) evaluate the accuracy of soil test P methods for acid sandy soils.
Initial (fall 2001) soil pH at the study site was 5.1 and soil test P was low [6 parts per million (ppm) P, TAMU method]. Fertilizer treatments included six rates of P (0, 20, 40, 60, 80, and 100 lb P2O5/A) and two rates of N (200 and 300 lb N/A). Ryegrass yield in 2002 showed no significant response to N fertilizer above 200 lb N/A. However, in 2003 there was a significant increase (716 lb dry matter) from 200 to 300 lb N. There was a significant yield response to P fertilizer in 2003…in the range of 3,300 lb dry matter (DM)/A at the 100 lb P2O5/A rate. Response to P over the no P control ranged from 1,544 to 3,316 lb DM/A. The greatest economic response to P in 2003 was at 60 lb P2O5/A, where yield increase due to P was almost 3,100 lb DM/A. The first two years of results from this study have demonstrated the importance of P fertilizer in optimizing ryegrass yield and profitability in the central Texas region. However, more data are needed to substantiate and support this information. Therefore, support for this study is scheduled to continue for at least one more year. TX-48F