Chris D. Teutsch

Nitrogen Fertilization Rate and Application Timing Effects on the Nutritive Value and Digestibility of Crabgrass

Crabgrass (species) could provide high quality grazing for ruminant livestock in the mid-Atlantic region of the United States. However, little is known about managing crabgrass as forage in this region. This study was designed to evaluate the effect of N fertilizer rate and application timing on the nutritive value of crabgrass. Nitrogen rates ranging from 0 to 400 lb/acre were applied as a single application at seeding or as a split application, one-half at seeding and one-half after the first cutting. Crude protein concentration increased with N fertilization. In contrast, the effect of N fertilization on crabgrass fiber digestibility was variable and appeared to be linked to weather patterns and other factors. Results of the current study clearly indicate that crabgrass is highly digestible, possessing IVTD values in the range of 75 to 90%. Crabgrass could provide excellent quality forage during the summer months when cool-season grass growth is restricted by high temperature and intermittent rainfall. This species would likely be best for livestock classes with high nutritional requirements such as weaned calves, stockers, or lactating dairy cattle.

Nitrogen Fertilization Rate and Application Timing Effects on the Yield of Crabgrass

Crabgrass (Digitaria species) is a summer annual grass that could provide high quality grazing for ruminant livestock in the mid-Atlantic region of the United States. However, little is known about managing crabgrass as a forage in this region. This study was designed to evaluate the effect of N fertilizer rate and application timing on the yield of crabgrass. Nine N rates ranging from 0 to 400 lb/acre were applied as a single application at seeding or as a split application, one-half at seeding and one-half after the first cutting. Averaged over years, first harvest yield ranged from 800 to 4000 lb/acre and increased as N rate increased with maximum dry matter production occurring at 255 lb of N per acre. Second harvest yield was greatest when N was applied as a split application. This effect was most pronounced with ample rainfall. Total dry matter production, averaged over years, ranged from 3000 to 9000 lb/acre and increased as N rate increased with maximum dry matter production occurring at 305 lb of N per acre. Results support current recommendations for summer annual grasses of applying N at 60 to 80 lb/acre at seeding followed by N at 40 to 60 lb/acre after each harvest and suggest that crabgrass could be managed in a similar manner.

Risk analysis, analysis of variance: getting more from our data.

Analysis of variance (ANOVA) and regression are common statistical techniques used to analyze agronomic experimental data and determine significant differences among yields due to treatments or other experimental factors. Risk analysis provides an alternate and complimentary examination of the same data by determining yield probabilities for each treatment or factor. We generated and analyzed a synthetic data set to illustrate that data with similar means, as determined by ANOVA, can have markedly different probability distributions due to differences in standard deviations. We then applied the techniques to data from a five-year yield trial of twelve Bermudagrass cultivars. ANOVA detected significant year-by-cultivar interactions while risk analysis illustrated differences among the cultivars in yield stability and in the probabilities of achieving specific yield goals. Together, ANOVA and risk analysis provide a more complete view of the data that facilitates technical transfer of experimental results to producers and other end-users.

Soil pH Effects on the Shoot and Root Yield of Crabgrass

Recent research indicates that crabgrass (Digitaria species) could provide high-quality summer forage for ruminant livestock in the mid-Atlantic region. Limited data are available documenting the soil pH requirements of crabgrass grown as forage. A greenhouse study was designed to determine the effect of soil pH value on the germination and yield of crabgrass. Treatments consisted of three pH levels: 4.8, 5.5, and 6.3. Pots 8 inches across and 8.5 inches deep containing 10 lb of air-dried soil were seeded at a density of 25 seeds per pot and thinned to 14 plants per pot after germination was complete. Two harvests three to four weeks apart were taken. Within the range of 4.8 to 6.3, soil pH had no effect on crabgrass germination, shoot yields, or root mass in either harvest. These data indicate that crabgrass has potential to produce summer forage on acidic soils commonly found within the southeastern United States.