埔里地區茭白筍長期栽培之土壤肥力與地下水品質評估初探

Preliminary Study on Soil Fertility and Ground Water Quality Assessment Under Long-term Planting Water Bamboo at Puli Area in Taiwan

譚增偉(Tseng-Wei Tan) ； 張瑞明(Jui-Min Chang)

《土壤與環境》 18卷1&2期 (2015/12) Pp. 19-34

摘要

鑑於埔里茭白筍之特殊栽培、生理特性及飲用水水源水質保護區之重要性，建立了15處水質與土壤之環境品質監測點，定期採取地下水、灌溉水、土壤與植體樣本。調查顯示，一般農戶肥料用量極大，然肥料氮肥利用率極低，致土壤無機態氮含量極高(0-90 mg/kg，多為NH_4^+-N)，土壤有效性磷含量亦極高(30-460 mg/kg P_2O_5)，而有機田為42-110 mg/kg；導致土壤酸化嚴重，強酸性，土壤嚴重缺矽，僅8-22 mg/kg，又嚴重缺鎂，僅38-80 mg/kg。土壤缺矽、鎂、鈣等之養分不平衡，植株易出現營養障礙，並可能為茭白筍易發生胡麻葉枯病與銹病之因子之一。0.1 N鹽酸抽出之土壤重金屬含量均遠低於規定之標準值。至於地下水水質一般礦物元素含量均屬合理，尤其磷鐵錳均未被檢測出，顯示過多之磷肥均留於土壤中。但不同監測點硫之高低差極大，雖未超過標準亦屬偏高，應為肥料使然。而地下水重金屬含量整體言之均遠低於規定之基準值， 唯鋅、銅含量不同地點高低差異極大，有偏高或高者恆高情形，且鋅高銅亦高，可能與有機質肥料使用有關；砷、鎘含量則有出現超過第一類地下水監測基準值者，唯未連續出現。地下水NH_4^+-N監測值出現超過第一類地下水NH_4^+-N監測基準值 0.05 mg/L者；NO_3^--N監測值雖未超過第一類地下水NO_3^--N監測基準值5 mg/L，亦屬偏高；而地下水總氮量監測值有超過灌溉用水水質標準Total-N 3.0 mg/L者。此反映出埔里茭白筍產區土壤加入了太多之肥料，相當量的氮己進入地下水。強烈的土壤還原特性如有機栽培易使植株錳吸收過多而造成毒害作用，強烈的土壤酸性缺矽，植株矽含量低等，成為當地茭白筍產量不高原因之一。

關鍵字

茭白筍 ； 地下水 ； 重金屬 ； 土壤酸化

並列摘要

In view of the special cultivation, physiological characteristics of water bamboo and the importance of resource protection for soil and drinking water, it has been established 15 monitoring sites to take samples of ground water, irrigation water and soils regularly for environmental quality assessment at Puli area. The investigation shows that the fertilizer consumption by farmers are enormous, and much larger than the general amount of 3 times for the paddy field. However, the fertilizer nitrogen use efficiency is extremely low, because very high content of inorganic nitrogen and available phosphorus were found in soil for 0-90 mg/kg of NH_4^+-N and 30-460 mg/kg of P_2O_5, respectively. Thus, it leads to serious soil acidification, strong acidity, and the deficiency of soil silicon and magnesium, the content ranged only 8-22 mg/ kg for silicon and 38-80 mg/kg for magnesium. The nutrient unbalances on lack of soil silicon, magnesium and calcium, and the strong soil reduction easily lead to nutrition disorders of water bamboo and to induce the basal stalk rot, rust disease and brown spot disease of water bamboo. The contents of soil heavy metal extracted by 0.1 N HCl are far below the requirements of the standard value. As for the ground water quality, the contents of general mineral elements are relative low, especially for phosphorus, iron and manganese, which are not detectable, showing that excessively phosphate fertilizers still remained in the soil. Although the sulfur concentration does not significantly exceed the standard value, the concentration is a little too high and obviously different among monitoring sites, showing the result of applying higher fertilizers. For the heavy metal in groundwater, for overall, its concentrations are much lower the regulations, however, the differences of zinc and copper contents among locations are obvious, and may be something to do with monitoring baseline value by applying organic manure. For the arsenic and cadmium, its content has occasionally found more than the monitoring baseline value of the first kind of ground water, but the higher content was not occurred continuously during the period of investigation. Also, the concentrations of NH_4^+-N in some ground water wells were occurred more than monitoring regulation of 0.05 mg/ L for the first kind of ground water. Although monitoring value of NO_3^--N does not exceed the monitoring regulation of 5 mg/L for first kind of groundwater, it seems relatively high for some monitoring sites, while the monitoring values of total nitrogen in some ground water wells are over the standard baseline value of total-N 3.0 mg/L for the standard of irrigation water quality. These results reflect that the soils are applied too many fertilizers, and a considerable amount of nitrogen has been leached into the ground water. Strong soil acidity and accompanying shortage of soil silicon and magnesium content, silicon and magnesium deficiency in plant tissue and the characteristics of strong soil reduction such as causing manganese toxicity of the plant become as one of the factors restrict the productivity of water bamboo.

並列關鍵字

Water bamboo ； Groundwater ； Heavy metal ； Soil acidification