화학비료 및 퇴비 장기시용에 따른 벼 뿌리 분포 특성

무기질 비료 및 퇴비를 36년간 長期 시용한 논 토양에서 벼 뿌리의 분포양상을 규명하기 위하여 무비, 퇴비단용, 삼요소, 삼요소+퇴비, 삼요소+규산구의 벼 뿌리 관련 특성을 조사하였다. 본 시험은 평택통에 화삼벼를 주당 3본씩 손이앙 하였으며 삼요소구의 시비량은 N-P_(2)-O_(5)-K_(2)O ㎏ ㏊^(1)=150-100-100를 시용하였고 규산은 ㏊당 500㎏ 퇴비는 ㏊당 10,000㎏를 시용하였다. 근계특성 분포 특성을 요약하면 다음과 같다. 지상부의 건물중은 시비량이 많을수록 높은 경향이었다. 그러나 뿌리 건물중은 삼요소구에 비하여 삼요소+퇴비에서 많았으며, 총근장은 무비에서 컸다. 뿌리 건물중은 삼요소+퇴비구에서 높았다. 토심별 근장밀도(㎝ ㎝^(3))는 무비구의 株間下 0~5㎝에서 가장 높았고 토심이 깊어질수록 적어지는 경향이었고 株下와 株間下의 차이는 심토로 갈수록 적어지는 경향이었으나 퇴비단용구는 토심 15~20㎝의 株間下에서 株下와 차이가 컸다. 토시별 근중밀도(㎎ ㎝^(3))는 삼요소+퇴비구에서 가장 높았다. 비근장은 삼요소+규산구에서 가장 낮았다. 뿌리 깊이 지수는 퇴비단용구가 높았으며 근장으로 계산한 지수가 근중으로 계산한 지수보다 높았다. It is well known that root distribution of rice is a crucial factor for nutrient absorbtion and affect by soil fertility management. However, the findings on root distribution are limited due to laborious and tedious work. The characteristics of root distribution were investigated in long-term fertilizer experiment plots that were established in paddy soil, a fine silty family of typic Hal-paqueps (Pyeongtaeg series) in 1967. Fertilizer experiment plots of no fertilizer, compost, NPK and NPK+compost plot have been maintained consistently for the past thirty six years and NPK+silicate plot for the past twenty two years. In NPK plot, 150 kg N (urea), 100 kg P₂O_(5) (fused phosphate) and 100 kg K₂O (potassium chloride) per hectare have been applied. For NPK+silicate plot, 500 kg SiO₂ (silicate) was applied in addition to fertilizer in NPK plot. For the compost plot, 10,000 kg rice straw compost per hectare were applied. Root samples were taken from the positions of hill-center (below hill) and mid-point of four adjacent rice hills at heading stage by cylinder monolith (CM) method. The soil cores were sampled 20 cm depth from the soil surface and partitioned four into layers at an interval of 5cm. The soil particles surrounding roots were washed out with tap water. Length and weight of the roots in each soil layer were measured and root length density (RLD), root weight density (RWD), specific root length (SRL) and rooting depth index (RDI) were calculated. Total root length was measured by intersection method. Plant height, tiller and shoot dry weight were the highest in NPK+compost plot. But RLD of hill-center soil cores was the highest in no-fertilizer plots. In the soil cores from mid-point position of four adjacent hills, RLD at 15-20 cm soil depth was higher in compost plot than NPK plot. RLD in compost plots showed even distribution compared to those in chemic