Evaluation Of Dry Matter Productivity And Profitability For The Cultivation Systems Of Forage Crops

With the characteristics of high yield and good quality, Italian ryegrass (Lolium multiflorum Lam) is cultivated extensively in the southern agricultural region of China and Japan. As one of the most important forages in the world, silage maize (Zea mays L.) has characteristics of high nutritive value and good palatability. Thus, the establishment of forage production system based on Italian ryegrass and silage maize has crucial significance in the development of husbandry.This test evaluated the production potential of different varieties of Italian ryegrass and tropical grasses. Besides, the effect of sowing date and different levels of nitrogen fertilization on silage maize production was also included. On the basis of production potential evaluation, the dry matter productivity and profitability for the multiple cropping of silage maize and forage was also analyzed in this test.The results in the experiment of tropical grasses showed that the dry matter yield of the 2nd cut (Oct.) of tropical grasses was lower than that of the 1st cut (Aug.), the IVDMD declined significantly as well(p < 0.05). The dry matter yield of 5 species of tropical grasses was highest in rhodesgrass (cv. Callide), followed by guineagrass, Paspalum atratum, coloured guineagrass and lowest in rhodesgrass (cv. Katambora). Compared with other species, having conspicuous advantages of yield, tiller numbers and plant height may be the main reason that the dry matter yield was the highest for rhodesgrass (cv. Callide) and Paspalum atratum.The results in the experiment of Italian ryegrass showed that the optimum cutting time for fall sowed Italian ryegrass was from late April to early May. The dry matter yield of each variety of Italian ryegrass were sized down as follows: Waseyutaka>NS-1> Tachiwase>Inazuma>Wase-ou, in which Waseyutaka was considered as the best one among all the varieties for the advantages of high yield and IVDMD. Although the average growth rate was relatively high after harvest for Inazuma and Tachiwase, the two varieties were not perfect due to the low dry matter yield and IVDMD. In spite of high dry matter yield of NS-1, the IVDMD dropped remarkably in the later period. Therefore, the harvest of Italian ryegrass should be done by the end of April to maintain high yield and good quality. The results in silage maize experiment showed that increase in the application of nitrogen fertilizer would be helpful to raise silage maize yield and ear weight, and it is even obvious in the treatment of early sowing. Late sowing caused the decrease both in forage yield and IVDMD, however, this phenomenon could be changed by the increasing nitrogen application.Combined with the analysis of economic and ecological effect, it is showed that the production system of Italian ryegrass and silage maize of early-sowing had not only high dry matter yield, but low cost, high productive value. In addition, more amount of CO₂ that can be absorbed from the atmosphere into this system than others.