EFEKTIVITAS INOKULAN BRADYRHIZOBIUM DAN GALUR MUTAN KEDELAI TERHADAP KANDUNGAN N DAN HASIL DI LAHAN MASAM

One field experiment had been conducted at Institute for Research and Agricultural Technology Evaluation at Taman Bogo FieldSta,to screen some Bradyhyzobium inoculants on soybean mutant lines developed for acid soil.Inoculants evaluated were single strain B-22,and its mixed inoculants (B-22+B37), (B-22 + G49), and (B-22+TAL 102) on two soybean mutant lines No.07 and 58,and cv.Wilis as check variety. Plant growth and N yield were determined at pod development (R4) and grain maturity (R8) stages.The effect of inoculation significantly influenced nodul-ation and N yield and tended to increase plant dry weight 25%.Mixed inoculant (B-22+B-37) showed good symbiotic compatibility with the three soybean genotypes tested,whereas inoculant(B- 22+G49) only showed good compatibility with mutant line No.58.Cultivar Wilis had broader symbiotic spectrum as compared to mutant line No. 07 and 58.The effect of plant genotypes,and its interaction with inoculants were significant on grain and N yield.It was observed that at pod development stage,the plant growth of mutant line No. 07 were slower than the other genotypes but it had better nutrient translocation rate to grain which resulted grain yield of cv. Wilis. The results showed that this mutant line could be developed for this area

Cassava-Based Intercropping Systems on Sumatra Island in Indonesia: Productivity, Soil Erosion, and Rooting Zone

In Gunung Batin, the southern end of Sumatra Island, Indonesia, cassava is widely cultivated on gently sloping areas for starch materials. The monoculture system and/or the intercropping system without legume plants commonly adopted in this region may tend to accelerate soil degradation. The objective of this study is to compare the productivity among several cassava cropping patterns to propose the most beneficial one in this region. A field experiment of five cropping patterns {cassava (Manihot esculenta Crantz) single-cropping, three cassava-based intercropping patterns, and a crop rotation} was conducted for three years. The cropping pattern that recorded the highest net income varied with the year. In 1997, the driest year of the past several decades, cassava single-cropping was the highest in income. The proposed intercropping system {cassava/(maize ơ soybean ơ cowpea)} was the highest in 1998, a year with moderate rainfall. In 1999, when severe insect damage occurred to legume crops, the farmersżconventional intercropping was the highest. In an average of the three years, the proposed intercropping pattern was same as cassava single-cropping, although cowpea cultivation as the dry season cropping was not possible in this region. The amount of soil erosion was relatively high in cassava monoculture in comparison with the other intercropping and crop-rotation systems. Cassava roots penetrated to only 0.5 m deep and extended 1 to 2 m in a horizontal direction depending on the planting density. These results lead to the conclusion that the proposed cassava cropping system would be the most beneficial in terms of economy and control of soil erosion