Effects of long-term green manure application on the content and structure of dissolved organic matter in red paddy soil

Dissolved organic matter(DOM) plays important roles in soil biogeochemistry activity and nutrients transportation in soils, but studies regarding the long-term effects of green manures on the content and structure of DOM in red paddy soil have not been reported yet. A long-term green manure experiment established in 1982 was utilized to test the DOM contents in different treatments, and the spectral characteristics of DOM were investigated by using ultraviolet-visible(UV-Vis) spectrometry and Fourier transform infrared(FTIR) spectrometry. The experiment included four cropping systems: ricerice-milk vetch(RRV), rice-rice-rape(RRP), rice-rice-ryegrass(RRG) and rice-rice-winter fallow(RRF), among them, milk vetch, rape, and ryegrass are popular winter green manure species in southern China. The results showed that the content of dissolved organic carbon(DOC), which is widely used to estimate the concentration of DOM, was significantly promoted after the incorporation of green manures compared with the other sampling stages. The contents of aromatic groups and the degree of humification of DOM increased in RRV and RRP, suggesting more complex compositions of the soil DOM after long-term application of milk vetch and rape. The contents of phenol, alcohol and carboxylic acid group at the mature stage of early rice were significantly higher than those at the stage of after green manures turned over, especially for the RRV treatment. The absorption ratio of FTIR indicated that winter plantation of rape increased the aromatic-C/aliphatic-C ratio, and ryegrass increased the aromatic-C/carboxyl-C ratio. In conclusion, long-term planting of milk vetch and rape as green manures increased the degree of aromaticity, humification and average molecular weight of DOM, and made the DOM more stable in red paddy soil.

Effects of free iron oxyhydrates and soil organic matter on copper sorption-desorption behavior by size fractions of aggregates from two paddy soils

Effects of free iron oxyhydrates （Fed） and soil organic matter （SOM） on copper （Cu^2＋） sorption-desorption behavior by size fractions of aggregates from two typical paddy soils （Ferric-Accumulic Stagnic Anthrosol （Soil H） and Gleyic Stagnic Anthrosol （Soil W）） were investigated with and without treatments of dithionite-citrate-bicarbonate and of H2O2. The size fractions of aggregates were obtained from the undisturbed bulk topsoil using a low energy ultrasonic dispersion procedure. Experiments of equilibrium sorption and subsequent desorption were conducted at soil water ratio of 1：20, 25℃. For Soil H, Cu^2＋ sorption capacity of the DCB-treated size fractions was decreased by 5.9% for fine sand fraction, by 40.4% for coarse sand fraction, in comparison to 2.9% for the bnlk sample. However, Cu^2＋ sorption capacities of the H2O2-treated fractions were decreased by over 80% for the coarse sand fraction and by 15% for the clay-sized fraction in comparison to 88% for bulk soil. For Soil W, Cu^2＋ sorption capacity of the DCB-treated size fraction was decreased by 30% for the coarse sand fraction and by over 75% for silt sand fraction in comparison to 44.5% for the bulk sample. Cu^2＋ sorption capacities of the H2O2-treated fractions were decreased by only 2.0% for the coarse sand fraction and by 15% for the fine sand fraction in comparison to by 3.4% for bulk soil. However, Cu^2＋ desorption rates were increased much in H2O2-treated samples by over 80% except the clay-sized fraction （only 9.5%） for Soil H. While removal of SOM with H2O2 tendend to increase the desorption rate, DCB- and H2O2-treatments caused decrease in Cu^2＋ retention capacity of size fractions, Particularly, there hardly remained Cu^2＋ retention capacity by size fractions from Soil H after H2O2 treatment except for clay-sized fraction. These findings supported again the dominance of the coarse sand fraction in sorption of metals and the preference of absorbed metals bound to SOM in differently stabilized status among the size fractions. Thus, enrichment and turnover of SOM in paddy soils may have great effects on metal retention and chemical mobility in paddy soils.

Effects of Long-term Located Fertilization on the Contents and Composition of Organic Matter in Paddy Soil

To reveal variation of organic matter content in red paddy soil, Through a 27 years-located fertilization experiment in red paddy soil, the content and composi- tion of organic matter in paddy soil were studied in this paper. The result showed that： the dynamics of soil organic matter of the different fertilization treatments showed significant differences, in the premise of equal nutrient （nitrogen and phos- phorus and potassium）, combining application of organic-inorganic was benefited for the accumulation of organic matter in paddy soil than without fertilizer treatment or chemical fertilizer treatment; the dynamics of soil humic acid, HA and FA of chemi- cal fertilizer only and Combining application of organic-inorganic treatments had basi- cally the same trend, But the contents of humic acid, HA and FA of combining ap- plication of organic-inorganic treatments had been higher than that without fertilizer and chemical fertilizer treatment. Moreover combining application of organic-inorganic treatments was benefited for improving the contents of HA and FA, but decreasing HA/FA ratio as an extension of time. Combining application of organic-inorganic was benefited for improving the contents ol readily oxidizable organic matter. And the contents of soil organic matter in long-term experiment and the contents of readily oxidizable O.M were highly significant positive correlation and the contents of soil total nitrogen, avail nitrogen and potassium were significant positive correlation; the contents of soil readily oxidizable O.M and the contents of soil total nitrogen, avail- able P and rice yield were significant positive correlation. Thereinto, the correlation （r=0.818 1 ） between the rice yield and soil readily oxidizable O.M was higher than the correlation （r=0.802 0） between the rice yield and soil organic matter. It showed the soil readily oxidized organic matter had greater contribution to the rice yield.

The Changes in Guilin Paddy Soil Organic Matter and Rice Yield under Long-Term Fertilization

Rational fertilization is an important measure to increase crop yield and soil fertility. Through analysis,this paper aims to master the change characteristics of soil organic matter and rice yield under different fertilizer treatments,in order to provide an important reference for the sustainable use of soil and effective fertilization. Long-term( 19 years) rice crop rotation experiments in waterloggogenic paddy soil were conducted to investigate the change trend of crop grain yield and soil organic matter with time,reveal the dynamic characteristics and relationship between main fertility factors and crop yields using comparative analysis at three sites with conventional fertilization and non-fertilization in Guilin. The results showed that compared with previous years,the rice yield increased by 53% under the fertilization treatment and degreased by 66% under the control. Over the years,the average soil organic matter( SOM) content under fertilization treatment was 23% higher than under CK treatment. This indicates that chemical fertilizer and organic manure application can increase the rice yield and soil organic matter,and high rice yield can be attributed to the SOM increase.

Effects of natural organic matter on cadmium mobility in paddy soil: A review

Cadmium(Cd) contamination in paddy soil has caused public concern. The uptake of Cd by rice plants depends on soil Cd mobility, which is in turn substantially influenced by organic matter(OM). In this review, we first summarize the fate of Cd in soil and the role of OM. We then focus on the effects of OM on Cd mobility in paddy soil and the factors influencing the remedial effectiveness of OM amendments. We further discuss the performance of straw incorporation in the remediation of Cd-contaminated paddy soils reported in laboratory and field studies. Considering the huge production of organic materials(such as straw) in agriculture, the use of natural OM for soil remediation has obvious appeal due to the environmental benefits and low cost. Although there have been successful application cases, the properties of OM amendments and soil can significantly affect the remedial performance of the OM amendments. Importantly, straw incorporation alone does not often decrease the mobility of Cd in soil or the Cd content in rice grains. Careful evaluation is required when considering natural OM amendments, and the factors and mechanisms that influence their remedial effectiveness need further investigation in paddy soil with realistic Cd concentrations.

Responses of Wheat Production, Quality, and Soil Profile Properties to Biochar Applied at Different Seasons in a Rice-Wheat Rotation

In the rice-wheat rotation system,biochar(BC)can be applied at the initiation of the rice or wheat season.Here,we compared the effects of BC that were applied at two different crop seasons on wheat production,quality,and soil profile properties in a rice-wheat rotation system with nitrogen(N)fertilizer applied at 280 kg/ha rate.Results showed that both wheat grain production and N recovery use efficiency were influenced by BC applied at two crop seasons.Biochar application did not affect the total non-essential amino-acid,but when applied during wheat season,BC significantly(p<0.05)increased total essential amino acid in grain by 12.3%,particularly for the valine(+48.2%),methionine(+43.8%),and isoleucine(+10.3%).We found that BC significantly(p<0.05)decreased the pH of soil at 0–6 cm and 20–30 cm by 0.14–0.18 and 0.05–0.08 units,respectively.The NH4+-N content of the whole observed soil profile were reduced by BC application,however,the effect of BC on NO3–-N content varied with the application season and profile depth.Interestingly,BC applied at wheat and rice season significantly(p<0.05)improved topsoil N contents by 48.4%and 19.7%,respectively.In addition,data suggested that BC applied during wheat season performed better in enhancing soil available phosphorus,potassium,and organic matter contents.In conclusion,we suggest that the optimum application time of BC for enhancing crop production and quality(take amino-acid content for example)and improving soil fertility is at the initiation of the wheat season.

黄棕壤性水稻土有机质含量高光谱反演研究

以黄棕壤性水稻土为研究对象,利用ASD FieldSpec®4地物波谱仪获取土壤高光谱反射率曲线,分析土壤有机质(SOM)含量的分布形态和高光谱特征,基于原始光谱(R)、一阶微分(FD)、二阶微分(SD)、倒数的对数(LR)、倒数一阶微分(FDR)和对数一阶微分(FDL)这6种光谱数据,分别建立了黄棕壤性水稻土SOM含量偏最小二乘回归模型(PLSR)、支持向量机模型(SVM)和BP神经网络模型(BPNN),并比较分析了这3种模型预测精度的差异。结果表明:(1)SOM含量与原始光谱反射率呈弱相关关系,经FD处理后,光谱曲线特征突出明显,光谱FD、SD、FDR和FDL变换能有效提升光谱反射率与SOM含量的相关性。(2)PLSR、SVM和BPNN模型对SOM含量低值(1.98%)的预测效果均较差;数理统计有助于模型精度的评价。(3)SVM模型的预测效果整体优于PLSR和BPNN模型;光谱FD变换的SVM模型对SOM含量的预测效果最好,其验证集的R2、RMSE和RPD分别为0.902、0.257和2.287,可为实现快速、准确地测定黄棕壤性水稻土SOM含量提供新的模型参考和技术思路。

淹水条件下水稻对土壤砷转化的影响

淹水条件下土壤砷的移动性和生物有效性显著提高,易被水稻吸收;然而水稻种植过程对土壤砷转化的影响机制尚不明确。选取了含低砷(15.5 mg∙kg^(-1))和高砷(52.1 mg∙kg^(-1))两种稻田土壤,每种土壤在淹水条件下分别设置种植和不种植水稻两种处理,在淹水培养期间的第7、14、28、42、56天采集土壤孔隙水、根际土壤,并在水稻成熟时采集水稻植株各部位样品。分析了不同砷形态、土壤砷组分、亚铁浓度、土壤溶解性有机质分子组分等的动态变化,探究了水稻对淹水土壤砷转化的影响机制。结果表明,与不种植水稻处理相比,种植水稻降低了淹水期土壤有效态砷和无定型铁铝氧化物结合态砷的比例,但提高了土壤腐殖酸结合态和富里酸结合态砷的比例。在第28天时种植水稻使孔隙水中溶解态Fe(II)质量浓度从43.6-51.3 mg∙L^(-1)降低至11.9-19.4 mg∙L^(-1),使土壤吸附态Fe(II)质量分数从1.14-1.21 g∙kg^(-1)提高至3.73-4.28 g∙kg^(-1)。三维荧光光谱分析表明,种植水稻显著提高了土壤溶解性有机质中类富里酸、类腐殖酸、类酪氨酸和类色氨酸等组分的丰度,且相关性分析结果表明,四者均与土壤有机质结合态砷呈显著正相关(p≤0.05或p≤0.01),但与土壤可利用态砷呈显著负相关(p≤0.01或p≤0.001)。此外,在高砷土壤种植的水稻呈现直穗病,这可能跟高砷土壤溶解性有机质中CHOS和蛋白质/脂质化合物的相对丰度(16.4%和12.0%)比低砷土壤(12.8%和6.62%)高有关。水稻植株可能通过根际响应和根系吸收等作用,降低土壤有效态砷,提高土壤溶解性有机质的含量,并使更多砷与土壤有机质结合,有利于砷的固定。

水旱轮作对土壤pH、有机质和重金属含量的影响

在水旱轮作模式下分水作和旱作2次采样分析了土壤pH、有机质含量及重金属污染物的分布变化规律。结果表明,水旱轮作情形下,水作pH、有机质含量比旱作整体偏高,偏高点位占比分别为85.7%、76.2%;重金属砷、铅、铜、镍、锌含量旱作比水作高,偏高的点位占比分别为61.9%、88.1%、64.3%、76.2%、69.0%,仅铬含量水作比旱作高,偏高的点位占比为71.4%。与旱作相比,水作pH中位值高0.55,增幅为8.0%,有机质含量中位值高9.6 g/kg,增幅为35.6%,砷、铅、铜、镍和锌含量中位值分别下降8.2%、9.2%、11.7%、7.8%、4.8%,而铬含量中位值则增加了14.3%。

水田土壤中水溶性有机物的产生动态及对土壤中重金属活性的影响:田间微区试验

采用田间微区试验研究不同施肥处理对土壤水溶性有机物 (DOM)的动态变化及其对土壤Cd活性的影响 结果表明 ,与施化肥对照处理相比 ,施用有机肥后土壤中DOM含量明显增加 .但随着水稻的生长DOM呈不断下降的趋势 ,而对照处理的变幅不大 ;在水稻整个生长过程中根际DOM含量不断增加且都高于对应时期土壤DOM的含量 ,并至水稻扬花期最大 ,此时 ,3种处理的根际产生DOM浓度 (DOM浓度以水溶性有机碳 (DOC)计 ,以下同 )分别为 :绿肥与化肥配施处理组 (GM) ( 14 0 2mg·L-1) >猪粪与化肥配施处理组 (PM) ( 11 12mg·L-1) >对照处理组 (F) ( 10 8mg·L-1) .水稻扬花期后 ,各处理的DOM含量不断下降 .试验还指出 ,有机肥施用后根际及土体土壤中交换态及有机结合态Cd含量显著增加 ,是对照处理的 2倍之多 ,同时发现 ,水稻收获后土壤交换态Cd的含量与此时的土壤DOM含量呈明显的正相关 (r土体 =0 92 6 6 ,n =8;r根际 =0 9389 ,n =8) .

基于全谱数据挖掘技术的土壤有机质高光谱预测建模研究

可见/近红外高光谱技术与建模方法是当前土壤近地传感器研究领域的重要方向,可应用于土壤养分信息的快速获取和农田作物的精确施肥管理。以浙江省水稻土为研究对象,利用以非线性模型为核心的数据挖掘技术,包括随机森林、支持向量机、人工神经网络等方法分别建立了不同建模集和验证集的原始光谱与有机质含量的估测模型。结果表明:研究比较的1∶1,3∶1和全部样本建模并全部验证的三种样本模式划分对建模的结果有一定的影响。相较于目前常用的偏最小二乘回归(PLSR)建模方法而言,非线性模型RF和SVM也取得了较好的建模精度,三种模式下其RDP值均大于1.4。特别是采用SVM建模方法所得模型具有很好的预测能力,模式二下其RDP值达到2.16。同时引入ANN方法改进建立的PLSR-ANN方法显著提高了PLSR的模型预测能力。

施肥对红壤性水稻土颗粒有机物形成及团聚体稳定性的影响

土壤颗粒有机物 (POM)是土壤有机碳库中活动性较大的碳库。POM的形成对提高土壤碳库和缓解大气CO2 的升高具有重要意义。POM的形成与土壤团聚体的形成和性质密切相关 ,且深受土地利用和土壤管理的影响。实验土壤采自江西省红壤研究所无机肥长期定位试验地 ,各施肥处理为 :CK(不施肥 )、NPK(施氮磷钾肥 )、NPK(=) (施双倍氮磷钾肥 )和NPK +OM(施氮磷钾肥和猪粪处理 )。研究发现 :施肥显著地增加了水稻土POM的含量 ;随着化肥施肥量和有机肥的增加 ,POM含量增加 ,NPK、NPK(=)和NPK +OM处理的POM含量比CK分别增加了 1 1～ 1 3倍、1 2～ 1 4倍和 1 5～ 1 9倍 ;施肥也提高了土壤团聚体稳定性 ,表现为NPK +OM >NPK(=) >NPK >CK ;各处理POM含量随土壤团聚体粒级的减小而增加 ,其C/N比为降低趋势 ;团聚体稳定性与POM含量呈极显著关系 (r=0 98,p <0 0 1)。

红壤稻田土壤有机质的积累过程特征分析

通过田间采样分析 ,研究了不同利用年限红壤稻田土壤有机质含量的变化及其过程和机理 ,确定达到平衡状态时红壤稻田土壤的有机碳含量水平。结果表明 ,在水耕条件下 ,土壤有机碳和全氮的积累过程可大致分为快速增长和趋于稳定阶段 ,水耕利用 30年 ,0～ 2 0cm土壤有机碳含量达到 2 0gkg- 1,全氮含量 1 6gkg- 1,随后 ,即使利用年限长达 80年 ,土壤有机碳和全氮含量变化趋于稳定 ,没有显著提高。 2 0天的培养期内 ,不同利用年限红壤稻田 0～ 1 0cm土层有机碳和有机氮的矿化率分别为 2 2 %～3 3%和 2 8%～ 6 7% ;总体来说 ,有机碳、氮的矿化率随红壤水稻土的熟化过程而升高。随着利用年限的增加 ,微生物生物量碳一直保持增加的趋势 ,而微生物生物量氮在利用 30年后其增加趋势明显趋缓 ;利用30年的红壤稻田 ,0～ 1 0cm土壤微生物生物量C、N为 332 8mgkg- 1和 2 3 85mgkg- 1,比利用 3年分别高1 1 1 %和 4 7%。与利用 3年的红壤稻田相比 ,利用 30年后细菌数量增加了 1 1倍 ( 0～ 1 0cm)和 3 8倍 ( 1 0～2 0cm) ,利用 80年后更显著地增加了 1 9倍 ( 0～ 1 0cm)和 1 2倍 ( 1 0～ 2 0cm) ;真菌的数量也呈上升的趋势 ,但在 30年利用后基本趋于稳定 ;此外 ,细菌的群落从荒草地的 4个种到 30～

不同肥料长期施用下稻田镉、铅、铜、锌元素总量及有效态的变化

以中国科学院桃源农业生态实验站的长期田间定位试验为基础,研究了16年长期定量施肥对土壤Cd、Pb、Cu和Zn积累及其有效性的影响。结果表明:单施化肥可使土壤Cd含量降低、Pb含量增加,对Cu和Zn的积累无显著影响,水稻收获时的移出效应可能是Cd含量降低的主要原因;与单施化肥相比,有机物料循环可提高土壤Cd和Pb的积累,但对Cu和Zn的积累无显著影响。试验期内单施化肥对土壤Cd、Pb、Cu和Zn的有效性无显著影响;有机物料循环可显著提高Cd和Zn的有效性,这与有机物料循环引起的土壤有机质含量增加和pH降低有关。

菌渣还田对稻田土壤养分动态变化的影响

为探讨菌渣还田对土壤肥力的影响,在大田试验条件下,研究不同菌渣(F)与化肥(C)配施对水稻生育期内土壤养分含量动态变化的影响。结果表明:在水稻的整个生育期内,菌渣与化肥配施能够明显提高土壤有机质、碱解氮、有效磷和速效钾含量,其中处理C100F100对土壤有机质的积累、提高土壤有效磷和速效钾水平作用最强,处理C100F50次之;处理C100F50提高土壤碱解氮的能力最大。综合考虑,在本试验条件下,处理C100F50可维持较高的土壤肥力,节约化肥施用及降低成本,实现废弃菌渣还田资源化合理利用。

江苏省土壤有机质变异及其主要影响因素

土壤有机质在陆地生态系统中具有重要作用,是估算土壤碳储量、评价土壤肥力和质量的重要指标。从省域尺度上分析土壤有机质的分布和变异,及其影响因素,对节能减排和土壤的可持续利用具有重要的指导意义。以江苏省第二次土壤普查的1519个土壤剖面数据为基础,分析了江苏省表层(0—20 cm)土壤有机质分布、变异及其影响因素。结果表明,全省土壤有机质平均含量为(16.55±8.49)g/kg,变异系数为51.36%,属中等变异水平。不同土壤类型有机质含量差异较大,沼泽土最高,为31.60 g/kg,棕壤最低,为8.69 g/kg;自然土壤的有机质含量变异程度大于耕作土壤。年均温、年均降雨量、成土母质、土地利用、土壤质地和土壤pH对全省土壤有机质含量变异的综合能解释能力为52.6%。土壤质地和年均温是有机质含量变异的主要影响因素,土壤质地对其变异的影响大于年均温,二者能够独立解释其变异的32.0%和23.4%。

成土母质对水稻土高光谱特性及其有机质含量光谱参数模型影响的初步研究

以青紫泥 (BlueclayeyPaddysoil,BP)和红黄泥 (RedPaddysoil,RP)为例 ,研究发育于不同母质的水稻土高光谱和SOM含量光谱参数模型的差异性。结果表明 ,发育于河湖沉积物的BP的反射系数总体上高于发育于第四纪红色粘土母质的RP ,在与铁的氧化物有关的吸收波段 ,RP的吸收特性较BP强 ;RP的一阶微分的变化趋势总体上也比BP剧烈 ,特别是与铁的氧化物相关的波段及 2 2 0 0nm处 ;BP与RP的SOM的光谱参数模型所包含光谱波段的个数和位置有较大的差异 。

耕地土壤有机质空间变异性的随机模拟

有机质是土壤重要的肥力特征,研究盐渍土改良区耕地土壤有机质空间变异特征可为土壤质量提升提供科学依据。以山东省禹城市盐渍土改良区典型地块耕地土壤有机质为研究对象,在全面野外调查和室内化验分析以获得大量的土壤有机质相关信息的基础上,运用地统计学方法对有机质进行了序贯高斯模拟各次实现(SGSV)、序贯高斯模拟平均实现(SGSA)和ordinary Kriging插值(OK),并将SGSV、SGSA、OK与实测数据进行了统计参数、变异函数、空间分布趋势等方面进行了对比分析。结果表明OK、SGSA改变了有机质数据的空间结构,具有"平滑"效应,SGSA在消除平滑影响方面优于Kriging插值;SGSV具有与实测数据相同的空间自相关结构,对预测点的模拟值具有不确定性,为揭示研究区域土壤有机质的空间结构特征提供了有力的工具,对盐渍土改良区土壤有机质空间不确定性的风险研究具有更实际的意义。

保护性耕作对稻田土壤有机质的影响(英文)

研究使用常规犁耕-休闲(DTF),常规犁耕-小麦(DTW),保护耕作-休闲(CTF),保护耕作-小麦(CTW)4个处理,评价连续实验10a后保护性耕作对稻作区SOM的影响。结果表明:垄作、免耕和小麦种植的结合是稻作区一种较好的保护性耕作实践。它不仅显著增加SOM在土壤表层的聚集,而且它也通过改变SOM的组成和结构显著影响土壤胡敏酸的光谱和热解特性。相比其他处理,垄作免耕(稻麦)在0～10cm土层拥有最多的SOM含量,但随着土层厚度的增加,这一含量下降的也较为迅速。垄作免耕(稻麦)土壤胡敏酸在波长665nm处的光密度为0.122,465nm处为0.705,而常规平作(中稻)在这两个波长处却分别为0.062和0.321。垄作免耕土壤胡敏酸DTA曲线在360～365℃处放热峰的焓变值比常规平作低,1000～1050cm-1吸收峰常规平作也比垄作免耕强。垄作免耕土壤腐殖质的氧化稳定系数增高,表明长期垄作免耕土壤腐殖酸的缩合度增高,芳构化程度增强。通过保护性耕作和作物实践可以管理稻田土壤,维持充分的SOM积累,缓解土壤有机碳的丢失。

应用耕作指数评价耕作措施对双季稻田土壤质量的影响

【目的】采用耕作指数(TI)定量评价了耕作措施对双季稻田土壤质量的影响,旨在为选择合理的土壤耕作措施提供依据。【方法】试验始于2005年,在湖南省宁乡县设免耕(NT)、旋耕(RT)和翻耕(CT)3个处理,测定了2007、2008年水稻收获期0—20 cm土层有机质(SOM)、土壤容重(BD)、全氮(TN)及pH等理化性状指标,利用目的线性回归模型计算TI。【结果】有机质含量和土壤容重对双季稻田土壤质量影响显著,水稻产量与土壤有机质含量显著正相关(R2=0.45),与土壤容重显著负相关(R2=0.67);可通过测定有机质含量和土壤容重计算得到TI,TI=0.40 SOM'+0.60 BD',且与水稻产量呈显著正相关(R2=0.67),可作为选择耕作措施的依据。试验中3个耕作处理土壤质量均有不同程度的改善,TI变化表明试验期间NT处理初期土壤质量较差(TI=0.79),但其TI增加最快,免耕能有效地改善土壤质量。【结论】利用目的线性回归模型计算TI能够较准确的定量描述不同耕作措施下双季稻田土壤质量。免耕有利于土壤质量的改善。