有机–无机肥配施比例对双季稻田土壤质量的影响

Effect of different application ratios of chemical and organic fertilizers on soil quality in double cropping paddy fields

【目的】利用江西省稻田土壤质量演变定位监测试验为平台,系统分析长期不同施肥措施下土壤质量状况,明确提升红壤性双季稻田土壤质量的优化施肥措施。【方法】长期定位试验设置8个处理,分别为不施肥处理(CK),施磷钾肥处理(PK),施氮磷肥处理(NP),施氮钾肥处理(NK),施氮磷钾肥处理(NPK),施70%化肥+30%有机肥处理(70F+30M),施50%化肥+50%有机肥处理(50F+50M),施30%化肥+70%有机肥处理(30F+70M),于2012年晚稻收获后测定2个土壤物理性质指标(容重和总孔隙度)、7个基础化学性质指标(有机质、全氮、全磷、碱解氮、有效磷、速效钾和p H值)及3个生物学性质指标(细菌、真菌和放线菌数量),分析长期不同施肥对各土壤性质的影响,并运用主成分分析对各处理土壤质量进行综合评分,最后将综合得分进行聚类分析,以评价长期不同施肥措施对红壤性双季稻田土壤质量的影响。【结果】经28年连续不同施肥处理后,各土壤性质在处理间均产生显著差异,但各土壤性质在处理间的变化趋势并不完全一致。化肥配施有机肥处理较化肥处理土壤容重降低12.7%~20.6%,土壤孔隙度增加2.3%~17.4%,有机质增加22.5%~41.8%,全氮和碱解氮分别提高9.8%~20.9%和11.1%~30.3%,全磷和有效磷分别提高11.1%~71.7%和1.31~1.75倍,p H值提高0.19~0.48个单位;主成分分析方法将原12个土壤性质指标降维、提取出2个主成分,反映了原信息量的87.4%,有机质、容重、真菌、全氮、有效磷、放线菌、总孔隙度、细菌、全磷和碱解氮在第一主成分上有较高载荷值,p H值和速效钾在第二主成分上有较高载荷;各施肥处理下土壤质量综合水平高低排序为:30%F+70M>50F+50M>70F+30M>NPK>NP>NK>PK>CK;聚类分析方法将长期不同施肥制度下稻田土壤质量划分为一级(30F+70M),二级(50F+50M、70F+30M),三级(NPK、NP),四级(NK、PK、CK)4个等级。【结论】与单施化肥相比,有机无机配施可有效增加土壤养分含量,改善土壤物理性质,缓解土壤酸化,提高土壤微生物数量,是提高红壤性双季稻田土壤质量的有效施肥措施。

[ Objectives ] A long-term paddy soil quality evolution experiment started from 1984 in Jiangxi Province was conducted to systematically analyze soil quality of double-rice cropping field in red soil region, and acquire the optimum fertilization measures to improve soil quality. [ Methods ] The long-term experiment included eight treatments, control （CK, no nutrient input）, phosphorus （P） and potassium（K） fertilizer treatment （PK）, nitrogen （N） and P fertilizer treatment （NP）, N and K fertilizer treatment （NK）, N, P and K fertilizer treatment （NPK）, 70% chemical fertilizer and 30% organic fertilizer treatment （70F ＋ 30M）, 50% chemical fertilizer and 50% organic fertilizer treatment （50F ＋ 50M）, and 30% chemical fertilizer and 70% organic fertilizer treatment （30F ＋ 70M）. Two soil physical properties （soil bulk density and total porosity）, 7 basic chemical properties （organic matter, total N, total P, available N, available P, readily available K and pH） and 3 biological properties （the number of bacteria, fungi and actinomycetes） were determined after the harvest of late rice in 2012. Effects of the long-term fertilization on soil properties were analyzed. Principal component and cluster analysis were used to evaluate the effect of long-term different fertilization systems on soil quality of double-rice cropping field in red soil region. [ Results ] The significant differences of soil properties were founded among the treatments. Compared with the chemical fertilizer treatments, the long-term application of chemical fertilizer and organic manure reduced soil bulk density by 12.7%-20.6%, and increased soil total porosity by 2.3%-17.4%, increased organic matter, total N, available N, total P and available P by 22.5%-41.8%, 9.8%-20.9%, 11.1%-30.3%, 11.1%-71.7% and 131%-175%, respectively. In addition, the soil pH in the treatments of chemical fertilizer combined with organic manure were increased by 0.19-0.48 than those of the chemical fertilizer treatments. The 2 principal components which could reflect 87.4% of the original information were extracted from the initial 12 indices. In the first principal component, organic matter, bulk density, fungi, total nitrogen, available P, actinomycetes, total porosity, bacteria, total P and available N had higher load value, while pH and readily available K had higher load value in the second principal component. The levels of soil quality under different fertilization treatments were sorted as follows： 30F ＋ 70M 〉 50F ＋ 50M 〉 70F ＋ 30M 〉 NPK 〉 NP 〉 NK 〉 PK 〉 CK. The soil quality of paddy soil under the long-term different fertilization systems was divided into 4 grades： first grade （30F ＋ 70M）, second grade （50F ＋ 50M, 70F ＋ 30M）, third grade （NPK, NP）, and fourth grade （NK, PK, CK）. [ Conclusions ] The study suggested that chemical fertilizer combined with organic manure can increase soil nutrient content compared with chemical fertilizer, improve soil physical properties, reduce soil acidification and improve soil microbial counts. Thus, chemical fertilizer combined with organic manure is the most effective fertilization measure to improve the soil quality of double-rice cropping field in red soil region.