对比研究槽式堆肥处理不同畜禽粪便对植物毒性的影响

为揭示槽式堆肥过程中不同畜禽粪便堆肥理化性质的变化及其对植物毒性的影响，分别开展了以羊、牛、鸡、猪粪便与木屑为堆料、为期44 d的好氧槽式堆肥对比试验，采集了不同堆肥期的堆肥样品，测定了堆肥的pH、电导率（EC）、可溶性有机碳（DOC）、硝氮（NO₃^--N）、氨氮（NH₄⁺-N）、全氮（TN）、碳氮比（C/N）、全磷（TP）、全钾（TK）、铜（Cu）、锌（Zn）含量及水堇的相对生长指数（RGI）和种子发芽指数（GI），并通过相关分析和线性回归拟合，分析了堆肥过程粪便对水堇种子植物毒性的影响机制.结果表明，槽式堆肥过程中，羊粪的高温期持续时间最长，牛粪其次，猪粪和鸡粪最短；堆肥结束时4种粪便均呈弱碱性.堆肥过程中猪粪和鸡粪的EC降低，其他粪便的EC变化幅度较小，各粪便的DOC、NH₄⁺-N含量降低，NO₃^--N、TP、TK、Cu和Zn含量增加，牛粪和鸡粪的C/N逐渐降低，而猪粪和羊粪的C/N呈先升后降的趋势，羊粪和猪粪的TN含量下降，鸡粪和牛粪的TN含量缓慢上升.堆肥过程中4种粪便对水堇种子的植物毒性均降低，且RGI和GI升幅由高到低为：牛粪 > 羊粪 > 鸡粪 > 猪粪.相关分析表明，堆肥过程中羊粪的TP、Cu、Zn，牛粪的Zn、TK、TP、NO₃^--N，鸡粪的NO₃^--N、TN、Cu，猪粪的NO₃^--N、TP、Zn、TK与RGI呈显著正相关（p<0.01）；而羊粪的Cu、TP、TK，牛粪的Zn、TK、TP，鸡粪的Cu、TN、NO₃^--N、TK，猪粪的TP、Zn、NO₃^--N与GI呈显著正相关（p<0.01）.由此表明，不同粪便堆肥的以上指标促进了植物的根伸长和种子发芽.但堆肥过程中羊粪的NH₄⁺-N、TN、DOC，牛粪的NH₄⁺-N、DOC、C/N、EC，鸡粪的C/N、EC、DOC，猪粪的NH₄⁺-N、DOC、EC与RGI呈显著负相关（p<0.01）；羊粪的NH₄⁺-N、TN、DOC，牛粪的NH₄⁺-N、DOC、C/N，鸡粪EC、DOC、C/N，猪粪的NH₄⁺-N、DOC、EC与GI呈显著负相关（p<0.01）.由此表明，不同粪便的以上指标显著抑制了植物的根伸长和种子发芽.多元回归分析说明，堆肥过程羊粪和牛粪的NH₄⁺-N，鸡粪的NO₃^--N、Cu、C/N和EC，猪粪的NO₃^--N和TK对水堇种子根伸长具有显著的影响，而羊粪的NH₄⁺-N和TK，牛粪的DOC、pH和EC，鸡粪Cu、TN和NO₃^--N，猪粪的TK对水堇种子发芽具有显著的影响.以上对比研究结果可为不同畜禽粪便槽式堆肥处理和土地利用提供重要的理论依据和决策支持.

Comparison of changes of different animal-manures composted by trough composting process and their effects on phytotoxicities

To reveal changes of physicochemical properties of animal-manure composts during trough composting and their effects on phytotoxicities, four kinds of representative compost samples of animal manures (including sheep-, cattle-, chicken- and pig-manures) were collected at different time of the composting over 44 days. Some key physicochemical properties of each compost sample including pH electrolytic conductivity (EC), dissolved organic carbon (DOC), NO₃^--N, NH₄⁺-N, total Kjeldahl nitrogen (TN), C/N ratio, total phosphorous (TP), total potassium (TK), copper (Cu), zinc (Zn), germination index (GI) and relative growth index(RGI) of cress were analyzed and compared. Some crucial factors influencing upon phytotoxicities of compost to the cress were determined by correlation analysis and multiple linear regressions. Results indicated that the composting temperature of sheep manure was the first to start sharp increase and lasted the longest time at the thermophilic stage, followed by those of cattle-, pig- and chicken-manures. The composts of all kinds of animal manures were weakly alkaline at the end of the composting. In the process of the composting, EC values of composted pig- and chicken-manures decreased. Change magnitudes of the EC values for cattle- and sheep-manure composts were small. The decreased concentrations of DOC and NH₄⁺-N whereas increased concentrations of NO₃^--N, TP, TK, Cu and Zn were found during the composting of all kinds of animal manures. The C/N ratios in cattle- and chicken-manure composts decreased gradually during the composting, while those in pig- and sheep-manure composts increased at the starting stage of the composting and decreased then. Concentrations of TN in the sheep- and pig-manure composts decreased, while those in chicken- and cattle-manure composts increased slowly during the composting. The RGIs and GIs for all animal-manure composts increased during the composting process, indicating their reduced phytotoxicities. In the process of the composting, the increasing magnitudes of the RGIs and GIs were of such order for different animal manures:cattle manure > sheep manure > chicken manure > pig manure. Correlation analysis showed that the RGIs had significantly positive correlations with concentrations of Cu, TP and Zn in sheep-manure composts, Zn, TK, TP and NO₃^--N in cattle-manure composts, NO₃^--N, TN and Cu in chicken-manure composts, and NO₃^--N, TP, Zn and TK in pig-manure composts (p<0.01). The GIs had significantly positive correlations with concentrations of Cu, TP and TK in sheep-manure composts, Zn, TK and TP in cattle-manure composts, Cu, TN, NO₃^--N and TK in chicken-manure composts, and TP, Zn and NO₃^--N in pig-manure composts (p<0.01). Those properties of the composts could promote root elongation and seed germination of cress. The RGIs had significantly negative correlations with concentrations of NH₄⁺-N, TN and DOC in sheep-manure composts, NH₄⁺-N, DOC, C/N and EC in cattle-manure composts, and C/N, EC and DOC in chicken-manure composts, NH₄⁺-N, DOC and EC in pig-manure composts (p<0.01), while the GIs had significantly negative correlations with concentrations of NH₄⁺-N, TN and DOC in sheep-manure composts, NH₄⁺-N, DOC and C/N in cattle-manure composts, EC, DOC, and C/N in chicken-manure composts, and NH₄⁺-N, DOC, and EC in pig-manure composts (p<0.01). Those physicochemical properties of the composts could inhibit root elongation and seed germination of cress. Multiple linear regression analysis indicated that concentrations of NH₄⁺-N in sheep- and cattle-manure composts, NO₃^--N, C/N, Cu and EC in chicken-manure composts, and NO₃^--N and TK in pig-manure composts had significant effects upon the root elongation of cress, while concentrations of NH₄⁺-N and TK in sheep-manure composts, DOC, pH and EC in cattle-manure composts, Cu, TN and NO₃^--N in chicken-manure composts, and TK in pig-manure composts had significant effects on seed germination of cress. The findings in the present study can provide important theoretical basis and decision support for trough composting of different animal manures and their recycling for land uses.