本文分別就歷年臺中縣農業總生產、農業總投入之變動加以分析，並由農業總產出與總投入指數計算臺中縣農業生產力及生產效率，觀察戰後臺中縣農業成長與衰落的趨勢。臺中縣農業生產在1950-1980 年間維持增長趨勢，1980 年代前期達農業產出的最高峰，至1983 年以後才逐漸呈現衰減趨勢，較臺灣農業生產衰落的時期，約遲了10 年。從歷年農業總投入的變動觀察臺中縣農業發展的趨勢，可以發現影響臺中縣農業生產指數下滑的主要因素是農業勞動人口與農業耕地的減少，但這兩項影響農業發展逐漸衰退的因素並非同步發生。儘管從1970 年代開始，臺中縣農村即已出現勞動力外流以及作物面積衰減的情形，但由於農村出現勞動力流失的現象並不明顯，且外移的主要是農村裡邊際生產力較低的剩餘勞動力，農家在單位面積上仍能保有相對充裕的勞動力，且有助於重新調整農業勞動投入與產出的關係。從資源投入對農業生產的貢獻觀察，戰後臺中縣農業發展在1950 年代農業重建階段之後，1960 年代主要是依賴提高資本集約度，達到農業生產增長之目的。當臺灣1970 年代出現農業衰退現象時，臺中縣則是藉由維持勞動集約度，持續農業生產的增長趨勢。直到1980 年代，當臺中縣農業勞動力流失的現象已進一步影響農業發展所需的勞動力時，在農業勞動力與耕地面積減少的情形下，農業生產再次藉由提高資本集約度，實現整體農業之增長。資本集約度是有其限制性，當作物栽培面積減少到一定程度時，1980年代後期臺中縣農業資金投入的邊際生產力便開始下降。再者，當土地租金與工資日漸高昂，提高土地租金與工資投入並不表示有效增加作物面積與勞動人數投入，同時也會對整體資金投入的配置出現排擠現象。更重要的是，當作物面積與勞動力出現嚴重衰減至影響整體農業發展的規模時，農業生產終將出現衰退的情形。

The study analyzes the total agricultural production of Taichung County over the years and the fluctuation in the total agricultural inputs, respectively. The indexes of total agricultural output and total agricultural input are used to calculate the agricultural productivity and production efficiency of Taichung County, and observe the post-war trends of agricultural growth and decline in Taichung County. The agricultural production in Taichung County maintained the growth trend in 1950-1980, and the agricultural output reached its peak in the early 1980s. A gradually declining trend started to appear after 1983, which was ten years later than the declining period of agricultural production in Taiwan. The observation on the fluctuation in the total agricultural input over the years suggested that the major factors leading to the decline in the agricultural productivity index were the reduction in agricultural labor force and the reduction in arable land. However, these two factors leading to the gradual decline in agricultural development did not occur simultaneously. Although the situation of labor migration and decline in reduction in arable land started to appear in 1970s, the phenomenon of labor migration in rural villages was not significant, and the labor migrated was the surplus labor of lower marginal productivity. Therefore, the labor force per unit area in rural villages remained abundant and could help re-adjust the relationship between agricultural labor input and output. The observation on the contribution of resource input to agricultural production indicated that after the stage of agricultural reconstruction of post-war agricultural development in Taichung County in the 1950s, the purpose of increasing agricultural production in the 1960s was achieved mainly by increasing capital intensity. When the phenomenon of agricultural decline rose in the 1970s, Taichung County continued the growth trend of agricultural production by maintaining labor intensity. In the 1980s, the phenomenon of agricultural labor loss in Taichung County further affected the labor force needed for agricultural development. Under the circumstance of the reduction in both agricultural labor force and crop area, the purpose of increasing the overall agricultural production was again achieved by increasing the capital intensity. Capital intensity has its limitations. When the crop area was reduced to a certain extent, the marginal productivity of agricultural capital input in Taichung County in the late 1980s started to decline. Moreover, when the land rent and daily wages gradually increased, the increase in land rent and wage input might not effectively increase crop area and the number of labor input. On the other hand, it might limit the allocation of overall capital input. It could be concluded that when the severe reduction in crop area and labor force affected the overall agricultural development, the agricultural production would decline eventually.