[Effects of manure substituting chemical nitrogen fertilizer on rubber seedling growth and soil environment.]

The substitution of manure for chemical nitrogen fertilizers has great impacts on the growth of rubber seedlings and soil environment, with implications for rubber cultivation and transplantation and soil environment improvement. In this study, rubber seedlings of thermal research '7-33-97' strain were cultivated under four treatments: No fertilizer application (CK), only application of chemical fertilizer (N), manure replacing 50% chemical fertilizer (M+N), and manure replacing 100% chemical fertilizer (M). Plants parameters (including plant height, basal diameter, biomass, and chlorophyll), soil physicochemical properties (including pH, soil organic carbon and nitrogen, soil enzyme activities), and their relationships were investigated. The results showed that plant height, basal diameter, biomass, and chlorophyll content in the M+N and M treatments were significantly higher, while underground biomass and root-shoot ratio were significantly lower than those of in N treatment. Compared with CK, soil pH was significantly increased in the M treatment, decreased in the N treatment, and was not changed in the M+N treatment. Soil ammonium and nitrate content in the M+N and M treatments were significantly lower, while soil organic carbon content, the activity of β-1,4-glucosidase (BG), β-1,4-N-acetylglucosaminidase (NAG) and leucine aminopeptidase (LAP) were significantly higher than those of in N treatment. Results of correlation analysis showed that soil pH was negatively correlated with soil ammonium and nitrate content, but positively correlated with BG and NAG activities. The structural equation model analysis showed that soil pH had significant positive effects on seedling quality index, while nitrate content had significant negative effects, and soil enzyme activities had no significant effect. Those results indicated that soil pH and nitrate content were the important driving factors on the growth of rubber seedlings. The manure replacing of 50% and 100% chemical nitrogen fertilizer could promote rubber seedlings growth, improve soil environment, and promote sustainable development of rubber production in Danzhou City, Hainan Province.研究有机肥替代化学氮肥对橡胶幼苗生长和土壤环境的影响对橡胶的培育移植和土壤环境的改善具有重要意义。本研究以热研‘7-33-97'品系橡胶幼苗为材料,以等氮(每株幼苗4.63 g全氮)替换的方式设置不施肥(CK)、单施化肥(N)、有机肥替代50%化肥(M+N)、有机肥替代100%化肥(M)4个施肥处理,分析了有机肥替代化学氮肥后橡胶幼苗株高、基径、生物量、叶绿素等生长指标和土壤pH值、土壤碳氮养分、酶活性等理化指标的变化及相互关系。结果表明: M+N、M处理株高、基径、生物量、叶绿素含量显著高于N处理,地下生物量、根冠比显著低于N处理;与CK相比,M处理土壤pH值显著升高,N处理显著降低,M+N处理无显著差异;M+N、M处理土壤铵态氮、硝态氮含量显著低于N处理,土壤有机碳含量及β-1,4-葡萄糖苷酶(BG)、乙酰氨基葡萄糖苷酶(NAG)和L-亮氨酸氨基态酶(LAP)活性显著高于N处理。苗木生长指数、土壤理化指标、土壤酶活性的相关性分析表明,土壤pH值与土壤铵态氮、硝态氮含量呈显著负相关;BG、NAG活性与土壤pH值呈显著正相关。结构方程模型分析表明,土壤pH值对苗木质量指数有显著正影响,硝态氮含量对苗木质量指数有显著负影响,3种土壤酶活性对苗木质量指数的影响不显著。可见,土壤pH值、硝态氮含量为调控橡胶幼苗生长的重要因素。在海南省儋州市,有机肥替代50%和100%的化学氮肥可促进橡胶幼苗生长,改善土壤环境,促进橡胶生产的可持续发展。.