Studies on Job's-tear as Forage Crop : 1. Herbage production and chemical composition of fodder Job's-tear millet (Coix Lacryma-Jobi L. var. frumentacea Makino)

Abstract

In the present study, Job's-tear millet as a forage was cutivated in order to clarify the herbage productivity and the suitablity in chemical composition. Fodder Job's-tear millet, cultivar Okayama Zairai, was sown on May 20 in 1982, at 0.8kg seed with drilling per are in a well-draind paddy field. The amounts of nitrogen, phosphorus and potassium applied before sowing and after the first cropping were each 2.0 and 1.5kg per are as compound fertilizer (15-15-15). Watering was practiced by intermittent irrigation thoughout seasons from the five-leaf stage. Fodder Job's-tear millet was cut at the heading stage (21/July) for the first cropping and at the milk-ripe stage (22/Sept.) for the second cropping. Investigation was performed periodically at intervals of one week during growing seasons. The following results were obtained: 1) Fodder Job's-tear millet was grown vigorously under submerged paddy condition. The total yield was 1, 029kg per are in green herbage and 192kg in dry matter. 2) The range of crop growth rate (CGR) during first cropping was 17〜37DM・g^<-1>・m^<-2>・day. The optimum leaf area index was estimated about 6.8 from the relation between CGR and mean leaf area index (Fig.1). 3) In the chemical composition, the contents of crude protein, crude fat, NFE, crude fiber and crude ash were 11.1, 3.7, 40.2, 32.0 and 13.0% at the first cropping, and 8.3, 2.5, 43.4, 33.8 and 12.0% at the second cropping, respectively. The contents of calcium, phosphorus, magnesium and potassium were 0.28, 0.16, 0.17 and 3.02% at the first cropping, and 0.38, 0.13, 0.14 and 2.28% at the second cropping, respectively. The contents (%) of calcium, phosphorus, magnesium and potassium varied during herbage seasons, in the range from 0.38 to 0.24, 0.25 to 0.11, 0.29 to 0.13 and 4.33 to 1.88 respectively. The contents of phosphorus, magnesium and potassium in the herbage decreased slowly with advancing maturity, but that of calcium increased. 4) It is judged from the above results that fodder Job's-tear millet showed a high herbage productivity under a submerged paddy field, but its contents of inorganic elements such as calcium, phosphorus and magnesium are below the mineral requirment for milking cow.