磷肥有机替代、秸秆还田对土壤化学性质和棉花产量及其构成的影响

Effects of organic replacement of phosphate fertilizer on soil chemistry and cotton yield and composition

新疆有机肥资源丰富,探索磷肥有机替代、秸秆还田的外源肥料投入对土壤化学变化、棉花产量及其构成的影响,为深入了解当前棉田肥力和确定棉花减磷增效的技术服务着力点提供参考依据。经国家灰漠土肥力与肥料效益监测基地5年田间微区定位试验,在膜下滴灌条件下设置7个施肥处理,T1:不施肥,T2:不施磷,T3:常规施化肥磷100%,T4:有机肥磷替代25%化肥磷,T5:有机肥磷替代50%化肥磷,T6:化肥磷100%+25%有机肥磷,T7:化肥磷100%+秸秆还田。于2022年采集土壤样品,探明不同比例磷肥有机替代、秸秆还田对土壤化学性质、磷素有效性特征和棉花产量及其构成的影响。研究结果表明:(1)在外源肥料投入量(有机肥和化肥)均为等氮磷用量的条件下,磷肥有机替代、秸秆还田有利于加速土壤养分转化,增加土壤速效养分、全量养分含量。速效氮、有效磷、速效钾含量增幅分别在3.0%~25.3%、29.2%~120.1%、70.1%~99.1%之间,各速效养分含量依次与外源肥料投入后增量最高的T6、T5、T5处理相比,年均分别增长3.12、1.69、30.75 mg·kg^(-1)。全氮、全磷、全钾含量增幅分别在21.1%~43.9%、1.59%~41.3%、9.3%~33.6%之间,各全量养分含量依次与外源肥料投入后增量最高的T6、T6、T5处理相比,年均分别增长0.04、0.05、1.36 g·kg^(-1)。整体上有机替代、增施有机肥和秸秆还田对促进土壤养分的转化效果比单施化肥好,且长期施用有机肥的效应优于秸秆还田。(2)耕层土壤有机质含量随有机肥替代量的增加而增加,50%的有机替代其有机质含量显著最高(12.21 g·kg^(-1)),年均增长0.4 g·kg^(-1),最小增量T1~T2与最大增量T1~T5相比,增加1.04~3.44 g·kg^(-1),增幅为11.86%~39.22%,总体表现为正效应。相对较高的土壤pH和盐含量是限制棉花高效生产的主要因素,有机肥和秸秆还田对土壤pH和含盐量整体起到降低的作用,最大降幅pH的T1与T5、盐含量T5与T3相比分别下降3.07%、24.48%,总体表现为负效应。配施有机肥和秸秆还田增强了土壤供氮能力和磷素活化能力,土壤磷活化系数从1.52%提升到2.78%。由于受新疆石灰性土壤自然特性及气候条件限制,综合C/N、C/P、N/P表明,灰漠土有机质处于缺乏状态。(3)磷肥有机替代和秸秆还田均能够维持或促进棉花增产,在密度为24万株·hm^(-2)的试验种植模式下,连续5年常规施肥、25%的有机替代、50%的有机替代、增施有机肥、秸秆还田其籽棉产量分别达4173.13、4196.72、4805.10、5035.51、4830.98 kg·hm^(-2),综合土壤养分指标、肥料投入、棉花产量分析,50%的有机替代在节约磷肥用量的前提下对棉花增产效果最佳,与T1、T2、T3相比,分别显著增产20.49%、18.62%、15.14%。因此,研究认为当下应用50%的有机替代技术,即施磷(P_(2)O_(5))60 kg·hm^(-2)和配施羊粪9784 kg·hm^(-2),较为可行。

Xinjiang was rich in organic fertilizer resources.This research aimed to explore the effects of organic replacement of phosphate fertilizer and exogenous fertilizer input of straw returning to field on soil chemical changes,cotton yield and its composition,so as to provide a reference for in-depth understanding of current cotton field fertility and determine the technical service focus of reducing phosphorus and increasing efficiency of cotton production.In this study,seven fertilization treatments were set up under the condition of membrane drip irrigation through the 5-year field micro-area positioning experiment of national gray desert soil fertility and fertilizer benefit monitoring station.Seven treatments were set up,including T1:no fertilization,T2:no phosphorus application,T3:100% fertilizer phosphorus application,T4:organic fertilizer phosphorus replacement 25% fertilizer phosphorus,T5:organic fertilizer phosphorus replacement 50% fertilizer phosphorus,and T6:fertilizer phosphorus 100%+25% organic fertilizer phosphorus,T7:fertilizer phosphorus 100%+ straw return to the field.Soil samples were collected in 2022 to investigate the effects of organic replacement of phosphorus fertilizer with different proportions and straw returning on soil chemical properties,phosphorus availability characteristics,cotton yield and its composition.The results showed that:(1)Under the condition that the amount of exogenous fertilizer nitrogen and phosphorus input(organic fertilizer and chemical fertilizer)was equal,the organic replacement of phosphate fertilizer and the return of straw to field could accelerate the transformation of soil nutrients and increase the content of soil available nutrients and total nutrients.The increases of available nitrogen,available phosphorus and available potassium content ranged from 3.0% to 25.3%,29.2% to 120.1% and 70.1% to 99.1%,respectively.Compared with the T6,T5 and T5 treatments with the highest increment after the application of exogenous fertilizer,the contents of each available nutrient were annually increased by 3.12,1.69 and 30.75 mg·kg^(-1) on average,respectively.Total nitrogen,total phosphorus and total potassium content increased by 21.1%-43.9%,1.59%-41.3% and 9.3%-33.6%,respectively.Compared with the T6,T6 and T5treatments with the highest increment after the application of exogenous fertilizer,the contents of each total nutrient average annual increase rate were 0.04,0.05 and 1.36 g·kg^(-1),respectively.On the whole,the effect of organic replacement,increased application of organic fertilizer and straw returning to field was better than that of single chemical fertilizer,and the effect of long-term application of organic fertilizer was better than that of straw returning to field.(2)Organic matter content in the topsoil increased with the increase of organic fertilizer replacement amount.The maximum organic matter content of 50% organic replacement was 12.21 g·kg^(-1),with an average annual increase of 0.4 g·kg^(-1).The minimum increment of T1and T2 increased by 1.04-3.44 g·kg^(-1),compared with the maximum increment of T1-T5.The increase rate was 11.86%-39.22%,and the overall performance was positive.Relatively high soil pH and salt content were the main factors limiting the efficient production of cotton.The return of organic fertilizer and straw to the field could reduce soil pH and salt content as a whole.The maximum decrease of pH was T1 with T5 and salt content was T5 with T3,which decreased by 3.07% and 24.48%,respectively,showing a negative effect.Combined application of organic fertilizer and straw returning enhanced the nitrogen supply capacity and phosphorus activation capacity of soil,and soil phosphoras activation coefficient increased from 1.52% to 2.78%.Due to the limitation of calcareous soil and climatic conditions in Xinjiang,the C/N,C/P and N/P showed that the grey desert soil was in a state of lack of organic matter.(3)Organic replacement of phosphate fertilizer and straw returning could maintain or promote the increase of cotton yield.Under the experimental planting pattern with a density of 240000 plants·hm^(-2),the seed and cotton yield of conventional fertilization,25% organic replacement,50% organic replacement,increased application of organic fertilizer and straw returning to field reached 4173.13,4196.72,4805.10,5035.51 and 4830.98 kg·hm^(-2),respectively,for 5 consecutive years.Comprehensive analysis of soil nutrient index,fertilizer input and cotton yield,50% organic substitution had the best effect on cotton yield under the premise of saving the amount of phosphate fertilizer,and significantly increased the yield by 20.49%,18.62% and 15.14%,compared with T1,T2 and T3,respectively.Therefore,the present study concluded that the application of 50% organic substitution technology,namely the application of phosphate(P_(2)O_5)60 kg·hm^(-2) and combination application of sheep manure 9784 kg·hm^(-2),is more feasible.