(17(3):7-16)EFFECT OF LIME AND PHOSPHATE ON THE YIELD OF MILK VETCH (ASTRAGALUS SINICUS) IN CONNECTION WITH THEIR RESIDUAL EFFECT ON RICE

石門水庫建設完成後，在該區域轄內約有6,000餘公頃的旱地，均可轉作為水田。由於初期農民於對轉作稻田施肥不適當，稻谷收量低落，農民得不償失，對於轉作稻田多裹足不前。最近經農試所肥力測定與精密田間試驗結果，發現該地區普遍缺乏磷肥，栽植水稻時，若能施用充足磷肥，同時兼施氮鉀肥，可確保稻谷收量，每公頃在3,500~4,500公斤間。 旱地開墾為稻田，費用甚高，為減輕農民負擔，提高稻作收量，擬在冬季試種紫雲英。由於該地區土壤酸度高，磷素含量低，因此本試驗目的在探討石灰與磷肥對於紫雲英之效應及其對於後作水稻之影響，藉以明嘹在冬季期間，是否可以裡作紫雲英，供作家畜飼料之用，以增加農民之收入，減輕新墾水田農民之負擔。 本研究曾接受國家長期發展科學委員會之補助，並承農復會補助試驗經費，謹申謝忱。 These field experiments were carried out at Pinchin and Chungli to study the effect of lime and phosphate on the yield of milk vetch and residual effect on the growth of rice. Split plot design with five replications was used. Two levels of lime, O and the amount to regulate the soil pH to 6.0 were set in the main plots while three levels of phosphate, 60,120, and 18o kg P2O5 were set in the plots. The milk vetch was cut off the land after 128 days growth. The rice was harvested after 125 days’ growth at both two locations. The fresh weight of milk vetch and the grain weight of rice were used for the analysis of variance. The soils of all treatments were sampled for pH, organic matter, and available P, K test after the harvest of rice. From the experimental data, the following facts can be seen: (1) There were significant effect of lime and phosphate on the yield of milk vetch at both lecations. Lime and phosphate can inorcease the yield of milk vetch very markedly. (2) At Pinchin, the yields of rice of the plots where the milk vetch was growed previ-ously were much less than those where no milk vetch was growed. However, there was no marked difference in rice yield due to the effect of milk vetch at Chungli. (3) No effect lime on the growth of rice can be detected at both locations, (4) The yield of rice varied significantly with the amount of phosphate applied. (5) The soil available phosphate was depleted more much in the soil where lime had been applied and milk vetch had been planted previously than in the soil without lime and milk vetch at Pinchin. However, this was not true for the soil of Chungli where the soil has lower fertility than that of Pinchin