Monday, November 13, 2006

Planting Date and Forage Quality in Sunn Hemp.

Jorge Mosjidis and Susan Sladden. Dept. Agronomy & Soils, "Auburn Univ.,202 Funchess Hall", "Auburn Univ.,202 Funchess Hall", Auburn, AL 36849-5412, United States of America

Sunn hemp (Crotalaria juncea L.) is a summer legume used as animal fodder crop that is also widely grown as green manure and fiber crop in the tropics . There are several characteristics of sunn hemp that make it specially valuable as a animal fodder in late summer in the Southeast of the USA. The objective of this study was to determine if planting date would affect forage quality. Planting dates (May 11, June 20 and July 16, 2004) were arranged in a randomized complete block design with four replications. A random 4-plant sample was obtained from each plot immediately after the plants in each plot started to flowers. Leaves and stems were separated, weighed and dried at 60 C. Nitrogen content (N), neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent lignin were measured. Planting date affected the number of days needed for the plants to flower. Plants from the June planting flowered first followed by May and July. Whole plant observations indicated that percentage of leaves, N, NDF, ADF and ADL were not affected by planting date but ash content was higher for the May planting followed by the July and June plantings. Leaf composition parameters except ADL were affected by planting date. N content increased as planting date progressed whereas NDF, ADF and ash were higher at the May planting followed by the July and June plantings. Stem composition was not affected by planting date. Results from this preliminary test show that forage quality of leaves is excellent but stems have low quality. On the average sunn hemp plants had a fair forage quality that has the potential to be improved by some agronomic practices such as planting date, plant density and harvest time.