신개간지(新開墾地) 인산비옥도(燐酸肥沃度) 증진에 관한 연구(硏究) -I. 흡착량기준(吸着量基準) 시용법별(施用法別) 인산시용적량결정(燐酸施用適量決定)

Improvement of the Phosphate Fertility in a Newly Reclaimed Hilly Land. -I. Sorption Technique for the Estimation of P Requirement as Related to the Application Method

시험전 토양으로서 인산흡착실험을 행하고 Langmuir최대흡착량을 구하여 이의 5, 10, 20, 30%에 상당하는 인산을 야산신개간지에 전면 시비 혹은 구시비하고 대두를 재배하여 인산의 시용량 및 시용 방법과 대두 수량과의 관계를 분석하였다. 전면시비의 경우 대두의 수량은 최대시용량인 30%구까지 인산의 시용량과 더불어 증가하였다. 그러나 구시비구의 수량은 동량의 전면시비구보다 항상 높았으나 20%구에서 최대수량을 나타내었으며, 30%구에서는 다시 감소하였다. 구시비 5% 구의 수량은 전면시비 20%구의 수량과 비슷하고 구시비 10%의 수량은 전면시비 30%의 수량보다 17%나 높았다. 퇴구비를 1,000kg/10a 시용한 구시비 10%구의 수량은 퇴구비없이 인산만 시용한 구시비 10%구의 수량보다 14.6%가 높았으며 구시비 20%구의 수량과 대등하였다.

Langmuir adsorption maximum was used as a basis for the estimation of phosphate requirement as related to the application method to a newly reclaimed hilly land. The application rates of phosphate fertilizer were 4 levels corresponding to 5, 10, 20, and 30 percent of the Langmuir adsorption maximum which was determined by the laboratory experiment. The phosphate fertilizer was applied in two different methods of broadcast and band application. Yield of soybean on a newly reclaimed hilly land was greatly affected by the amount of phosphate fertilizer and application method. With the same amount of phosphate fertilizer, the soybean yield in the broadcast was always lower than that in the band application even though the yield in the broadcast increased with the application rate up to the highest level of this experiment. However, the yield in the band application showed steep increase up to 20 percent level and then the yield decreased at the highest level. The yield at the rate of 5 percent with the band application was equal to the yield at the rate of 20 percent with broadcast, and the yield at the rate of 10 percent with band application was higher by 17 percent than that in the highest broadcast rate. When manure was applied at the rate of 1000 kg/10a to the plot of the 10 percent band application, the yield was 14.6 percent higher than the yield of the plot of the 10 percent band application without the manure and was equivalent to the yield of the plot of the 20 percent band application.