我国褐土耕地质量的演变及对生产力的影响

Quality Change of Cinnamon Soil Cultivated Land and Its Effect on Soil Productivity

【目的】耕地质量是影响土壤生产力的关键因素,也是科学施肥的重要依据。褐土区为我国小麦和玉米的主产区,研究该区域31年间(1988—2018)耕地质量的演变,并分析它们对生产力的影响,为褐土区的科学施肥提供依据。【方法】基于31年全国103个褐土长期定位试验点的数据,分析褐土耕地质量的演变;并通过冗余分析,比较影响生产力的因素;在此基础上对褐土区的科学施肥提出了合理建议。【结果】(1)褐土区土壤理化性质的演变及现状:有机质、有效磷和速效钾2018年均值分别为17.9 g·kg^-1、29.2 mg·kg^-1和164 mg·kg^-1,监测期间分别提高了21.2%、200.9%和55.0%;全氮和缓效钾2018年均值分别为1.1 g·kg^-1和945 mg·kg^-1,监测期间趋于平稳;中微量元素和重金属含量数值分布在合理范围;pH下降0.3个单位;耕层厚度为21.9 cm,容重为1.33 g·cm^-3,均属于中等水平。(2)褐土区施肥量,2018年总量为730.2 kg·hm^-2,肥料氮(N)磷(P2O5)钾(K2O)的比例约为2﹕1﹕1,化肥与有机肥的比例约为3.45﹕1;氮肥用量378.9 kg·hm^-2,监测期间趋于平稳,磷肥和钾肥用量监测期内呈下降趋势,分别降低24.1%和50.8%。(3)31年间褐土区小麦产量呈上升趋势,监测末期达到6651 kg·hm^-2,比初期提高27.6%;玉米产量较为平稳,监测末期达到8851 kg·hm^-2,监测中期和末期均与初期无显著性差异。小麦季和玉米季的地力贡献率分别为49.0%和59.6%;对产量的影响,物理指标中耕层厚度(对小麦产量的解释率,2.7%)和容重(对小麦和玉米产量的解释率分别为1.2%和1.5%)的作用较大;化学指标中有机质对小麦、玉米产量的解释率均较高,分别为2%和1.7%,有效磷对玉米产量的解释率也较高(3.6%);肥料用量指标中,钾肥对小麦、玉米产量的解释率均最高,分别为5.6%和6%,其次,磷肥对小麦产量(1.3%)、氮肥对玉米产量(1.3%)的解释率也较高。【结论】31年间褐土的耕地质量得到提升,但是总体肥力偏低,物理指标处于中等水平。考虑耕地质量对生产力影响的基础上,对于小麦和玉米,需要制定不同的施肥方案,均需提高钾肥的投入,且重点保障小麦的磷肥和玉米的氮肥供应;对于物理指标需要引起高度关注,耕层和容重处于中等水平,但不需要继续优化,维持现状更利于获得高产。

【Objective】The quality of cultivated land is a key factor affecting soil productivity,which serves also as scientific basis for rational fertilization.Cinnamon soil is the main soil type at the production area of wheat and corn in China.This study examined the current status of cultivated land quality and the evolution characteristics of cinnamon soil during the past 31 years(1988-2018).Though considering the evolution of fertilizer application rate,their influence on productivity was studied,and the guidance for reducing fertilizer input and increasing efficiency in cinnamon soil area was proposed.【Method】Using the data of 103 long-term(31 years)location test points in China,the evolution of cinnamon soil cultivated land quality was analyzed by combining physical and chemical indexes.The factors influencing the yield were compared through the redundancy analysis(RDA).Based on these results,reasonable suggestions were put forward to reduce fertilizer input and increase efficiency in cinnamon soil area.【Result】(1)The present situation and evolution of soil physical and chemical properties in cinnamon soil area were shown in the study.Specifically,the average values of organic matter content,available phosphorus and available potassium in 2018 were 17.9 g·kg^-1,29.2 mg·kg^-1-and 164 mg·kg^-1,respectively,which represented an increase of 21.2%,200.9%and 52.0%during 31years,respectively.The average values of total nitrogen and slow available potassium in 2018 were 1.1 g·kg^-1 and 945 mg·kg^-1,respectively,which remained relatively stable during the monitoring period.The contents of soil secondary elements and micronutrient elements and heavy metals were in an acceptable range.The pH was reduced by 0.3 unit.Topsoil thickness was 21.9 cm and bulk density was 1.33 g·cm^-3,which belonged to the middle level.(2)The fertilizer application rate in cinnamon soil area was 730.2 kg·hm^-2 in 2018.The proportion of N(N):P(P2O5):K(K2O)was about 2:1:1,and the proportion of chemical fertilizer to organic fertilizer was about 3.45:1.The nitrogen fertilizer application rate was 378.9 kg·hm^-2,which was stable during the past 31 years.The application rate of phosphate and potassium fertilizer decreased by 24.1%and 50.8%,respectively.(3)The wheat yield showed an upward trend during 31 years,and the maximum reached 6651 kg·hm^-2 at the end of monitoring,which was 27.6%higher than the value at the initial stage.The corn yield was stable,reaching 8851 kg·hm^-2 at the end of monitoring.The contribution rate of soil fertility in wheat season and corn season was 49.0%and 59.6%,respectively.The yield was influenced by soil physical factors,including the thickness of plough layer(which could explain the wheat production for 2.7%,denoted as explanation rate),bulk density(explanation rates of wheat and corn productions for 1.2%and 1.5%,respectively)and chemical index,such as organic matter explanation rates of wheat and corn productions for 2%and 1.7%,respectively,and available phosphorus(explanation rate of corn for 3.6%).The explanation rates of potassium fertilizer were the highest for wheat and corn productions,which reached 5.6%and 6%,respectively.The explanation rates of phosphorus fertilizer for wheat yield(1.3%)and of nitrogen fertilizer for corn yield(1.3%)were also relatively high.【Conclusion】The cultivated land quality in cinnamon soil area has been improved in 31 years,but the overall fertility was low and the physical properties were in middle level.Considering the impact of land quality on productivity,different fertilization schemes needed to be formulated for wheat and corn.Both of which needed to increase the input of potassium fertilizers,and focused on ensuring the supply of phosphorus fertilizers for wheat and nitrogen fertilizers for corn.Physical indicators needed to be highly concerned.The topsoil thickness and bulk density were at a medium level,but there was no need to continue to optimize,and maintaining the status quo was more conductive to obtaining high yield.