轉作玉米田土壤肥力限制因子研究

Study on Fertility Constraints of the Paddies Converted for Corn Production

李子純(Tze-Shun Lee)

《中華農業研究》 37卷2期 (1988/06) Pp. 165-176

https://doi.org/10.29951/JARC.198806.0007

摘要

本研究係利用廳屬各農改場設於全省之轉作玉米田適栽標準栽培區進行者，研究期作及地點包括73年秋作共46點，74年春作共32點。進行方法爲於各標準栽培區整地施肥前採取其土壤樣本及剖面，前者作各項理化性質分析，後者爲瞭解各試區土系及底土性質、排水狀況等。玉米發芽後30-45 日採取值株樣本作葉片分析，以明瞭其營養狀況，並利用「診斷推薦綜合系統」(DRIS)方法計算各養分之指數(DRIS indices)，尋找限制因子，以與土壤分析資料對照。收獲後記錄其產量，目的爲探討本省各地轉作田之土壤肥力限制因子。同時在各標準栽培設無磷區，不施磷肥，以比較磷肥效果，期能獲得轉作田之玉米磷肥診斷標準。所得結果如下：
1.土壤性質與玉米產量的相關分析顯示玉米產量僅與土壤田間容水量成顯著負相關關係。土壤水分影響玉米發芽率及生長，與玉米產量確有最密切的關係。
2.轉作田土壤磷肥需要量無法依土壤有效磷（Bray P或Olsen P）含量高低決定。但由各試區內無磷區產量均無超過施磷區者可知磷肥對轉作田的重要。
3.磷肥效果以春作較高。無磷區產量百分率(NK/NPK×100)春作平均爲81.8，秋作爲89.7。其中又以北部及臺東地區磷肥效果最高。
4.土壤分析資料顯示轉作田土壤中，Fe、Mn及Mg在土層中均有明顯下移現象，而有效性P、K含量則表土遠高於底土。植物分析資料及由其計算出的DRIS指數更顯示玉米生長前期（發芽後至45日）普遍缺P、Mn及Mg而以K含量最高。玉米生長前期，土壤中較高的鉀含量顯然已經抑制玉米對Mg及Mn的吸收。
5.在針對前項限制因子改良的副試驗中，的確證實P及Mn的重要，而鉀的效果則只在排水較差地區較爲明顯。

並列摘要

This study was carried out on all the standardized corn cultivation plots laid out islandwide for corn adaptation on the converted paddies. Fourty-six plots in the autumn crop, 1984, and thirty-two plots in the spring crop, 1985 were included in this study.
Surface and sub-soil samples were collected from each of these plots be-fore land preparation and fertilization, physical and chemical properties were analyzed. Plant samples were taken twice: once for whole corn plants 30 to 45 days after emergence, and once for ear leaf at the silking stage. Nutrient concentration were determined and DRIS indices calculated for each element. To evaluate P response and P diagnostic criteria, 100m^2 within each of the 500m^2 plots applied no phosphorus. Yields were recorded after harvesting.
The results are summarized below.
1. Among all the soil properties, only the water holding capacity was significantly negative correlated with corn yield. Soil moisture is really the most important factor that effects the emergence and growth of corn.
2. Neither Bray nor Olsen's method can effectively extract the amount of phosphate that is available for the plants grown in the converted paddies. The fact that corn yield was always higher in the plots with P than those without it proves the necessity of P fertilization in those soils.
3. Yield response to phosphate was higher in the spring than autumn crop. The percentage yield without P (NK/NPK×100) were 81.0 and 89.7 respectively, and the best response was found in Northern Taiwan and Taitung area.
4. Soil analysis results shown that free Fe, easily reducible Mn and exchangeable Mg were obviously lower in the surface than sub-soil, while available P, K concentration were in the opposite way. Plant analysis data and the DRIS indices calculated from it indicated that there are widespread deficiencies of Mn, Mg, P and an excess of K among all these converted paddies in the early growth period (45 days after emergence) of corn,
5. In a subsiduary experiment carried out in 1986 in three field trials including both eastern and western Taiwan, phosphorus and manganese proved to be both beneficiary and potassium response was found only in the ill-drainage area.