低投入的有機芻料生產研究－指草屬（Digitaria spp.）與花生屬（Arachis spp.）混植

本研究以盤固草（Digitaria decumbens）A254及Survenola（D. × umiforia）各別混植多年生花生（Arachis grabrata）或蔓花生（A. pintoi），調查在不施肥狀況下草種組合的表現，以探討用於建立低投入永續草地或有機草地的可行性。結果顯示多年生花生雖初期生長速度慢，但建立後持久性良好，產量逐年上升，在混植區中提供相當可觀的比例；多年生花生與盤固草混植表現優於與Survenola混植。混植處理到第三年仍有 16-19 mt/ha的乾物產量，無混植者僅7 mt左右，禾豆混植不僅維持產量，且大幅改善收穫牧草的營養價值。割期試驗顯示，混植區於夏季延遲至90天才收穫者CP為9.4%，NDF為61%，ADF為43%，是相對較佳的熱帶牧草品質。其高營養價值主要來自豆科的高CP及低NDF，而禾本科本身生長減緩，也有助於品質的維持。本試驗歷次的收穫自土壤中移除了大量的礦物元素，以第三年禾豆混植區為例，總共自地上部收穫了217-277 kg/ha的氮素。在僅利用豆科的生物固氮，沒有施肥及放牧的情形之下，導致土壤總氮、有機質及其他土壤成分的降低，且高產小區的降幅較大。總結，多年生花生與盤固草可以在有機生產的目的下建立穩定的混植體系，但長期而言，需要利用放牧或適當的堆肥補充才能達成系統的養分平衡。

關鍵字

禾豆混植；有機草地；花生屬；指草屬

並列摘要

Mixed planting of pangolagrss (Digitaria decumbens, A254) or Survenola (D. × umiforia) between Arachis grabrata or A. pintoi were evaluated to investigate their feasibility in sustainable pasture or low-input production of organic pasture. A. grabrata had good persistence in the mixture, however, the initial growth rate was slow. The dry matter yield and the coverage ratio of A. glabrata in the mixture increased each year. Mixture of A. grabrata and pangolagrass was better than that of A. grabrata and Survenola. Dry matter yield of the mixture still maintained 16-19 mt/ha in the third year, while that of the monoculture, reduced to 7 mt/ ha. The results indicated that both forage yield and quality could be improved in grass-legume mixture as compared to those in monoculture. When the harvest stage was prolonged to 90 days in summer, the mixtures had CP 9.4%, NDF 61%, and ADF 43% which showed a relatively high quality as compared to tropic forage. The higher contents of nutrient in the mixture were due to higher CP and lower NDF contents of legume. Moreover, slow growth of grass also helped maintaining its forage quality. Large quantity of minerals was removed from the soil by cropping. For example, in the third year a total of 217-277 kg/ha of nitrogen was removed from the above ground part of the mixture. Under biological nitrogen fixation of the legume only, there was no fertilizer input or grazing in this system, and as a result, soil organic matter, total nitrogen, and other components declined in the plots with high productivity. It was concluded that mixed planting between A. grabrata and pangolagrass could form a stable grass-legume mixture for organic forage production. It is suggested that grazing or some quantity of compost is necessary to maintain the nutrient equilibrium of the cropping system in the long term.

並列關鍵字

Grass-legume mixture ； organic pasture ； Arachis ； Digitaria

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