Evaluation of the release of nitrogen and phosphorus in different soils affected by addition of four organic materials

土壤有機質含量為土壤品質的重要指標之一。有機質材的添加即為增加土壤有機質含量的主要策略，唯有機質材之氮和磷的釋出特性可能會受到土壤性質及有機質材本身特性的影響。本研究的目的在於探討四種不同特性之有機質材在三種不同性質土壤中的氮和磷釋出特性，以建立有機質材在土壤中的管理策略。 選用中部地區性質不同的土壤[大肚山(pH 4.8)、台中(pH 6.4)與圳寮(pH 7.7)]，分別加入分解速率差異大的大豆粕、禽畜糞堆肥、米糠及蔗渣堆肥(30公頓/公頃)，於25℃、-33kPa之水分含量下培育，分別於第1，2，4，6，10，15及20週，嗣測定各處理土壤之pH、有機碳、溶液磷、不穩定性磷、活性磷和磷酸鹽型態的含量。另選取大豆粕與禽畜糞堆肥，探討兩者之施用對三種供試土壤氮有效性的影響。 試驗結果顯示，有機質材的添加對土壤pH的影響效應，會與質材之鹼度及土壤本身pH有密切關係，因此禽畜糞堆肥的施用對強酸性大肚山的pH增進效應最為顯著；大豆粕的施用會使三種土壤產生酸化的現象。一般而言，蔗渣堆肥和米糠之施用對台中和圳寮pH的改變效應並不顯著。 有機質材增進土壤有機質含量的效果，與質材有機碳含量及組成分中所含難分解之木質素和半纖維素的多寡有關，因此以蔗渣堆肥的增進效果最佳，禽畜糞堆肥次之，而以大豆粕的效果最差。對不同性質土壤之有機質含量的增進效果，則以強酸性大肚山土壤 > 石灰性圳寮土壤 > 非強酸性及非石灰性台中土壤。 四種有機質材的施用對土壤磷有效性的增進效應，以總磷及無機磷含量最高的禽畜糞堆肥的效果最佳，而以大豆粕的效應最差。對不同土壤而言，由於台中土壤對磷的吸附能力最低，因此有機質材的施用所增進磷有效性的效果最為顯著，其次為石灰性圳寮土壤，而以強酸性大肚山的土壤效果最差。大豆粕含氮量高且較易分解，故施用於土壤後所釋出無機氮的量顯著高於禽畜糞堆肥。 綜合本試驗的結果可知，有機質材的選用宜視目的而定；如欲提高土壤有機質含量則以含難分解成分多的蔗渣堆肥較佳；若欲提昇土壤磷有效性則以禽畜糞堆肥較佳；若欲提昇土壤氮有效性則以大豆粕較佳。The organic matter content in soil is one of the important index of soil quality. The addition of organic materials is the best practice to increase soil organic matter, however, the release characteristics of nitrogen(N) and phosphorus(P) of organic materials have been suggested to vary with the characteristics of the organic materials and the soils used. The purpose of this study was to investigate the release characteristics of different organic materials in three soils varied with their properties, in order to develop a suitable management practice of organic materials in soils. Three different soils varying in their chemical properties [Da-Du-Shan(pH 4.8)], Taichung(pH 6.4), Chun-Liao(pH 7.7)]were selected in this study. Four organic materials (soybean meal, animal compost, rice bran and sugarcane dregs compost) were added into the soils at the rate of 30 t ha-1. During the whole incubation period, the soils was kept at -33kPa water potential and at 25oC. Soil samples were taken after incubation for 1day, 1, 2, 4, 6, 10, 15 and 20 weeks separately, and the pH, the contents of organic carbon, solution p, labile p, active p and p compounds of each treatment were determined. In addition , the effects of soybean meal and animal compost addition on mineral-N (NH4+ - N and NO3- - N) contents in three different soils also were investigated. Results showed that the effect of organic material addition on soil pH was closely related to the basicity of organic material and the initially pH of the soils, therefore, the greatest improving effect was found in strongly acidic Da-Du-Shan soil applied with animal compost, and acidification were found in all three tested soils as soybean meal were added. In general, three was no significant change of soil pH in Taichung and Chun-Liao soils as sugarcane dregs compost and rice bran were added. The increasing effect of soil organic matter content was shown to be related to the contents of organic carbon, lignin and hemicellulose of organic materials. Therefore, the greatest effect were found in the treatments added with sugarcane dregs compost, followed by added with animal compost, and the treatments with soybean meal were the least. Regard to the increasing effect of soil organic matter contents in the soils used were in order : strongly acidic Da-Du-Shan soil > calcareous Chun-Liao soil > non-acidic and non-calcareous Taichung soil. The increasing effect of soil p availabilities with animal compost addition was greater than other organic materials addition due to its higher content of total p and inorganic p, and the least effect were found in the treatments applied with soybean meal. As for different soils, the greatest increase of p availability was found in Taichung soil, followed by calcareous Chun-Liao soil and strongly acidic Da-Du-Shan soil. The amount of released inorganic N were higher in the treatments of soybean meal addition than those in the treatments of animal compost addition, due to soybean meal has higher N content and is easily decomposable. Overall results indicated that the choice of organic materials should base on the purpose we selected; sugarcane dregs compost is frequently high in difficultly decomposable components is the best choice to increase soil organic matter content, animal compost is the best choice to increase soil p availability and soybean meal is better to increase soil N availability.謝誌 i 中文摘要 ii 英文摘要 iv 目錄 vi 圖次 vii 表次 ix 壹、前言 1 貳、前人研究 3 一、有機質材的施用對土壤pH值的影響 3 二、有機質材在土壤中降解的特性 3 三、有機質肥料的添加對土壤磷有效性的影響 4 四、有機質肥料的施用對土壤氮有效性的影響 8 參、材料與方法 11 肆、結果與討論 20 一、有機質材的添加對土壤pH值的影響 20 二、有機質材的添加對土壤有機質的影響 31 三、有機質材的添加對土壤中磷行為的影響 40 (一)對土壤溶液磷濃度的影響 40 (二)對不穩定性磷(Labile P)的影響效益 49 (三)對土壤活性(Active)磷濃度的效應 57 (四)有機資材的添加對土壤中無機磷酸鹽含量的影響效應 63 四、有機肥料對土壤有效性氮及礦化的影響 69 伍、結論 78 陸、參考文獻 81 附圖 90 附表 9