Quantification Analysis of the Contribution of Environment, Soil, and Management Factors to Crop Yields : Case Study of the Yields of Rice, Potato, and Orange in Nagasaki Prefecture

Hayashi\u27s theory of quantification No.1 was used to examine the contribution of environment, soil, and management factors to crop yield in Nagasaki prefecture. The yields of paddy-rice, potato, and orange were considered. All the data employed in the quantification analyses were collected from the Dojo-kankyo-kiso-chosa (soil survey for improved utilization and conservation of soil resources) which was carried out as a national project from 1979 to 1987. The yield of paddy-rice was closely related to the items used in the study. Among the items, the most important item to control the paddy-rice yield was the environmental items of weather and physiography. Soil type (soil series) was well related to the averaged yield of paddy-rice under the same physiographic unit. The contribution of rice variety and rate of nitrogen fertilizer application to the yield was low compared with the contribution of soil type. Soil chemical properties hardly affected the paddy-rice yield. The correlation between the yield of potato and items was not so good. Items relating to environment less contributed to the yield than items relating to soil and management did. Among the items used, soil type, soil chemical property, and rate of nitrogen fertilizer application were important to control the potato yield. The yield of orange showed the higher correlation to the environmental items than to the soil and management items. The averaged yield of orange was well related to the physiographical environment, although the contribution of weather was not clear. The effect of soil chemical property on the orange yield was greater than the effect of rate of fertilizer and lime application. The phosphate-absorption coefficient of a soil may be a good index to the potential productivity classification of orange field consisting of Red-Yellow soils.長崎県の土壌環境基礎調査(定点調査)の1巡目と2巡目(昭和54～62年度)の調査で得られた資料をもとに,水稲,ばれいしょ,みかんの収量を外的基準として数量化分析Ⅰ類を行い,これら作物の収量に対する環境,土壌および管理要因の相対的な寄与について評価した.水稲収量には,気象および地文(地形･地質)環境が強く影響した.県レベルでの水稲収量は,この2つの要因によって予測されえた.土壌要因の寄与は環境要因に比べて小さいものの,地域レベルの水稲収量は土壌統と一定の対応関係を示した.水稲収量と土壌要因との関係では,土壌統や土壌統群など土壌型としての表示が,土壌の化学牲を用いるよりもうまく対応し,土壌統群は水稲品種や窒素施肥量など管理要因よりも強く水稲収量に関係した.ばれいしょ収量に対する環境要因の寄与は小さく,むしろ土壌要因がより強く関係した.施肥量や品種も,相対的に大きい寄与をみせた.土壌要因のなかでは,土壌統群と並んで士壌の化学性,特にリン酸吸収係数がばれいしょ収量と密接な関係を示した.施肥量では窒素肥料の効果が最も大きかった.みかん収量は地文環境に依存し,地域ごとに平均みかん収量が予測されえた.土壌要因のなかでは,土壌型の寄与が母材よりも大きく,土壌の化学性も一定の関係を示した.みかん収量には,肥培管理よりも土壌の化学性が大きく影響し,リン酸吸収係数が樹園地土壌の生産性を分級する場合のひとつの指標になると考えられた