土壤生態變異對土壤溶液有機碳境況之影響

Effect of Soil Ecology Variation on Organic Carbon Regime in Soil Solution

王敏昭(M. C. Wang)

《土壤與環境》 1卷3期 (1998/09) Pp. 249-268

https://doi.org/10.30058/SE.199809.0007

摘要

本研究之目的在探討添加不同有機材料對土壤溶液有機C境況之影響。添加至土壤之有機材料包括極易分解之綠肥，易分解之農產廢棄物堆肥，以及不易分解之泥炭。試驗田除了添加有機材料外，再添加不同氮肥量之處理，其用量為1/3與2/3之化學N肥量。試驗田種植之作物為水稻及鮮食用玉米之水旱輪作。然後，於85年5月至86年9月，不同作物生長期間，採集田間不同處理之四個重複小區的表土（0～15cm）及底土（15～30cm），分析其飽和抽出液之總有機C量（total organic C of saturationextract；TOC-S）。研究結果指出在第一期水稻種植期間（85年5月），七種處理土壤之TOC-S均為表土大於底土者。表土之TOC-S範圍為21.0 ± 10.3～31.5 ± 11.4 mg/kg；底土者為9.2 ± 4.7～17.7 ± 5.9 mg/kg。堆肥及堆肥+1/3 N處理者，其表土之TOC-S有較高之趨勢。相對的，對照、綠肥+1/3 N以及泥炭+1/3 N處理者，其表土之TOC-S則有偏低之趨勢。此結果指出在飽和土壤水分含量下，添加之堆肥較綠肥及泥炭為較佳之TOC-S供給者。同一處理之四個重複小區之土壤的TOC-S差異甚大。水稻收穫後（85年7月），田菁種植前，七種處理區之表土及底土的TOC-S驟降。其表土之TOC-S範圍為2.4 ± 1.5～5.7 ± 3.0 mg/kg；底土者為4.11 ± 1.9～5.5 ± 2.7 mg/kg。除了對照區外，其他六種處理之土壤的TOC-S均有底土大於表土之趨勢。除了對照區以外，水稻收穫後，隨著田菁之種植以及玉米之種植，各處理土壤之TOC-S有逐漸增加之趨勢。然而，至85年12月，玉米生長後期，此總有機C量再降至最低；然後，再逐漸昇高。至86年4月水稻生長期間，施用堆肥小區表土之TOC-S再昇高至18.0 ± 5.9 mg/kg，且與對照者（6.6 ± 2.6 mg/kg）及化肥-N者（9.2 ± 3.6 mg/kg）之差異趨勢愈大。至水稻生長後期及收穫，不同處理小區表土之TOC-S再降低至頗低之含量。兩次輪作，相對應作物之生長期間，不同處理小區表土之TOC-S及表土與底土之TOC-S的總和有規則性之週期。田間施用不同有機材料與不同土壤水分境況之生態變因共同影響土壤溶液有機C量之變化，此總（溶解性）有機C物質之物種及其特性值得深入探討。

關鍵字

持續農業 ； 生態 ； 溶解性有機物質 ； 生產力 ； 總有機C

並列摘要

The purpose of this study was to investigate the effect of the amendment of various organic materials on the organic carbon regime in soil solution. The amended organic materials included extremely decomposable green manure, easily decomposable compost derived from agricultural wastes, and resistively decomposable peat. Except for amending with organic materials, the experimental plot was also amended with chemical fertilizer nitrogen. The amounts of the additionally amended chemical fertilizer nitrogen were 1/3 and 2/3 of that amended in chemical fertilizer plot. The planted crops were the rotation of paddy rice and upland corn. From May, 1996, through September, 1997, the surface soils (0-15 cm) and subsoils (15-30 cm) of four duplicated blocks for each treatment in the field at different growth stages of the crops were collected and subjected to the analysis of the amount of total organic carbon of saturation extract (TOC-S). The results showed that, during the growth period of the 1st crop of paddy rice in May, 1996, the amounts of TOC-S of seven different treatments were higher on surface soils than on subsoils. The amounts of TOC-S of the surface soils were 21.0 ± 10.3 ~ 31.5 ± 11.4 mg/kg; those of the subsoils were 9.2 ± 4.7 ~ 17.7 ± 5.9 mg/kg. The amounts of TOC-S of the surface soils of the treatments of compost amended and of compost + 1/3 N amended have higher tendency. Correspondingly, those of the treatments of check, of green manure + 1/3 N amended, and of peat + 1/3 N amended have lower tendency. This indicates that, under saturated soil moisture, the plots amended with compost are better supply of the amount of TOC-S than those amended with green manure and with peat. The amounts of TOC-S among four duplicated plots of the same treatment varied greatly. After harvesting of paddy rice in July, 1996, and before planting of green manure, the amounts of TOC-S of the surface soils were 2.4 ± 1.5 ~ 5.7 ± 3.0 mg/kg; those of the subsoils were 4.1 ± 1.9 ~ 5.5 ± 2.7 mg/kg. Other than the check, the amounts of TOC-S of the subsoils of the remaining six treatments were higher than those of the surface soils. Except for the check, after the harvest of paddy rice, and the subsequent planting of green manure and then corn, the amounts of TOC-S of the soils from each treatment gradually increased. However, during the late growth period of corn in December, 1996, the amounts of TOC-S of the soils from each treatment again decreased to the least, and then gradually increased. During the growth stage of paddy rice in April, 1997, the amount of TOC-S of the surface soil from the treatment amended with compost increased to 18.0 ± 5.9 mg/kg which was much greater than 6.6 ± 2.0 mg/kg of the check and 9.2 ± 3.6 mg/kg of the treatment amended with chemical fertilizer-N. At later growth stage of rice and after its harvest, the amounts of TOC-S of the surface soils from the treatments then decreased to some extents. Two times of crop rotation, during the growth period of corresponding crops, the amounts of TOC-S of the surface soils from the treatments have regular periods. Ecological variances from both the application of various organic materials and various soil water regimes synergistically affect changes of the amounts of total (dissolved) organic carbon in soil solution. The characteristics of these total organic carbon substances is thus merit close attention.

並列關鍵字

Sustainable agriculture ； Ecology ； Dissolved organic substances ； Productivity ； Total organic carbon