保护性措施对中低肥力黑土区有机质变化的影响

为探索农户采用保护性措施对东北黑土区土壤有机质(SOM)变化的影响,通过跟踪2008年至2015年间梨树县19个乡镇341块农田SOM的变化,分析了免耕、秸秆还田和有机肥施用三项保护性措施采用情况对SOM变化的影响。2015年梨树县SOM平均为18.8 g·kg^-1,较8年前下降了10.5%(P<0.05)。土壤初始SOM含量越高,其SOM下降越明显。在初始SOM>20 g·kg^-1的区域,SOM显著降低,但在初始SOM≤20 g·kg^-1的区域,SOM含量较2008年提升了4.5%(15.3 g·kg^-1)。主要是因为SOM≤20 g·kg^-1区域采用过保护性措施的农户比例高达63.2%,而SOM>20 g·kg^-1区域农户采用比例为49.3%。同时发现在初始SOM较低的土壤,采用单项保护性措施可以维持甚至提高SOM,同时采用三项措施显著提升了SOM。但在初始SOM较高的土壤,两项措施结合才可维持SOM不下降。目前梨树黑土区保护性措施的采用可以维持甚至提高SOM,但在应用时需要加强应用时间的连续和技术间的集成。     

免耕条件下施用有机肥对冬小麦土壤酶及活性有机碳的影响

【目的】探讨免耕条件下施用有机肥对冬小麦土壤酶活性及活性有机碳含量的影响,明确免耕条件下的科学施肥方法,为提升土壤生物学活性和改善土壤质量提供理论依据。【方法】基于山西运城长期定位试验,选取免耕（NT）和免耕增施有机肥（NTM）两个处理,在冬小麦不同生育时期测定与碳转化相关土壤酶的活性（β葡萄糖苷酶、β木聚糖酶、纤维二糖苷酶、α葡萄糖苷酶）、土壤温度、土壤含水量和土壤呼吸速率以及成熟期土壤总有机碳（TOC）和活性有机碳组分（可溶性有机碳,DOC;易氧化有机碳,EOC;微生物量碳,MBC）等关键指标。【结果】（1）在冬小麦生育期,两个处理不同土壤酶活性具有明显的季节性变化特征。其中β木聚糖酶与α葡萄糖苷酶的活性在拔节期和灌浆期表现出升高趋势;但β-葡萄糖苷酶与纤维二糖苷酶的活性随季节变化波动较小。不同生育时期β木聚糖酶和α葡萄糖苷酶的活性的变化趋势与土壤呼吸速率变化趋势基本一致。此外,主成分分析结果表明,不同生育时期土壤酶活性主要受土壤含水量和土壤呼吸速率的影响。（2）与NT相比,NTM显著提高不同生育时期土壤β木聚糖酶的活性（越冬期：17.6%;抽穗期：8.5%;灌浆期：14.1%和成熟期：10.0%）;在越冬期和拔节期土壤α葡萄糖苷酶的活性分别提高16.7%和10.2%。同时,主成分分析结果表明,不同处理间酶活性主要受土壤温度和土壤呼吸速率的影响。（3）与NT相比,NTM显著提升冬小麦生长季TOC、DOC、EOC和MBC含量（TOC：16.9%;DOC：27.7%;EOC：38.4%和MBC：50.7%）。（4）冬小麦生长季土壤生物学指标相关分析表明,β木聚糖酶与α葡萄糖苷酶的活性与总有机碳及其活性组分呈显著相关关系（相关系数均大于0.850）。【结论】免耕增施有机肥通过影响生育期土壤含水量和土壤温度,进而提升β木聚糖酶与α葡萄糖苷酶的活性;同时,秸秆还田基础上增加有机肥碳投入可进一步提高土壤总有机碳和活性有机碳组分的含量,有利于土壤酶等生物学活性和土壤质量的提升。     

绿洲农田土壤团聚体组成及有机碳和全氮分布对秸秆还田方式的响应

通过田间定位试验，在甘肃干旱灌区，研究了不同小麦秸秆还田方式(NTSS: 25~30 cm 高茬收割立茬免耕; NTS: 25~30 cm高茬秸秆覆盖免耕; TIS: 25~30 cm 高茬秸秆深翻耕; CT: 传统不留茬深翻耕—对照) 对农田土壤团聚体及有机碳和全氮分布特征的影响，以期为优化试区种植模式与提高农业可持续发展提供依据。结果表明：免耕秸秆还田处理(NTSS、NTS)≥0.25 mm团聚体含量较高，与CT相比，在0~10、10~20、20~30 cm土层分别提高5.4%与12.5%、13.3%与14.1%、11.1%与19.2%，以NTS提高幅度较大。NTSS、NTS提高了0~10、20~30 cm土壤团聚体的平均重量直径，较CT处理分别提高6.7%与11.6%、7.6%与8.1%，以NTS提高效果最明显。NTSS、NTS处理土壤有机碳和全氮含量均高于 CT 处理，在0~10、10~20、20~30 cm土层，有机碳含量分别增大8.1%与13.3%、7.4%与11.4%、7.8%与12.8%；全氮含量分别提高14.6%与17.9%、14.5%与17.9%、16.2%与20.5%，同样，以NTS提高土壤有机碳及全氮程度较大。各级别团聚体中有机碳和全氮含量均随土层深度增加而减小，团聚体中有机碳和全氮含量随团聚体直径减小而增加，NTS处理在各土层各级别团聚体均保持较高的土壤有机碳及全氮含量。因此，前茬小麦25~30 cm秸秆覆盖免耕还田是干旱灌区增强土壤团聚体形成、提高土壤有机碳及全氮含量的适宜栽培措施。     

No-tillage effects on grain yield and nitrogen requirements in hybrid rice transplanted with single seedlings: Results of a long-term experiment

This study was conducted to determine whether, and if so how, the grain yield and nitrogen (N) requirements of hybrid rice transplanted as single seedlings are affected by no-tillage (NT) practices. A fixed field experiment was done at the Experimental Farm of Hunan Agricultural University in Changsha, Hunan Province, China, from 2004 to 2014. Grain yield and yield attributes (panicle number per m², spikelet number per panicle, spikelet filling percentage, grain weight, total biomass, and harvest index) were evaluated as well as the N-use characteristics (total N uptake, internal N-use efficiency, and N requirements) of hybrid rice transplanted as single seedlings comparing NT with conventional tillage (CT). A significant finding was that there were no significant differences in grain yield, yield attributes, and N-use characteristics between CT and NT. Averaged across the 11 years, grain yield and N requirements were 9.51 t ha^–1 and 20.2 kg t^–1 under CT and 9.33 t ha^–1 and 20.0 kg t^–1 under NT, respectively. There were significant yearly variations in grain yield, yield attributes, and N-use characteristics observed under both CT and NT. The yearly variation in grain yield was related to simultaneous changes in spikelet number per panicle, grain weight, total biomass, and harvest index. Also, it was found that grain yield was positively correlated with internal N-use efficiency but negatively correlated with N requirements. It is concluded that grain yield and N requirements in hybrid rice when transplanted as single seedlings are not affected adversely by NT. The results of this study suggest that (1) compatible relationships among yield attributes can be established in hybrid rice that is transplanted as single seedlings, and (2) higher grain yield and higher N-use efficiency can be concurrently achieved in hybrid rice transplanted as single seedlings.     

黑龙江省黑土地保护性耕作实施基本情况及问题研究

黑土有机质含量丰富,土壤养分高,是全球最优质的土壤资源之一,更是国家的宝贵战略资源。黑龙江省地处中国东北部,黑土区土壤肥沃,是国家重要的商品粮基地。但是近年来由于水土流失等原因造成黑土肥力下降、黑土层变薄等相关问题,需要全面推行黑土地保护性耕作方法。运用数据分析法,参考文献法等方法,对黑龙江省黑土地保护性耕作实施的基本情况及问题进行分析。在黑土地保护性耕作实施过程中,面临着农户对黑土地保护耕作方式认知程度偏低、技术运用不规范、技术种类和机具数量偏少、缺少黑土地保护性耕作长效机制等现实问题。因此,提议从提高农户认知程度、建立大面积黑土地保护性耕作示范基地、提升政府扶持力度、为黑土地保护性耕作技术研发和装备供给提供专项资金、建立黑土地保护性耕作长效机制等方面建设黑土地保护性耕作的发展之路。     

Time-variable soil hydraulic properties in near-surface soil water simulations for different tillage methods

Simulating near-surface soil water dynamics is challenging since this soil compartment is temporally highly dynamic as response to climate and crop growth. For accurate simulations the soil hydraulic properties have to be properly known. Although there is evidence that these properties are subject to temporal changes, they are set constant over time in most simulations studies. The objective of this study was to improve near-surface soil water simulations by accounting for time-variable hydraulic properties. Repeated tension infiltrometer measurements over two consecutive seasons were used to inversely estimate the hydraulic properties of a silt loam soil under different tillage - conventional (CT), reduced (RT), and no-tillage (NT). Simulated water dynamics with constant and time-variable hydraulic parameters were compared to observed data in terms of the soil water content and water storage in the near-surface soil profile (0-30 cm). The measurements indicate a considerable temporal variability in the saturated hydraulic conductivity, the field-saturated water content and the parameter α of the van Genuchten/Mualem model. Temporal variability was largest for CT and RT, whereas under NT, replicates of measured water contents and hydraulic properties showed a considerable large spatial variability. Simulations with time-constant hydraulic parameters led to underestimations of soil water dynamics in winter and early spring and overestimations during late spring and summer. The use of time-variable hydraulic parameters significantly improved simulation performance for all treatments, resulting in average relative errors below 13%. Since simulation results agreed with observed water dynamics in two seasons, the applicability of inversely estimated hydraulic properties for soil water simulations is demonstrated. Thus, simulations that address applied questions in agricultural water management may be improved by using time-variable hydraulic parameters. The simulated water balance indicated that RT and NT result in better water storage than CT and therefore may increase water efficiency under water-limited climatic conditions.     

冬种马铃薯稻草包芯栽培模式试验研究

对冬种马铃薯3种栽培模式（稻草免耕、稻草包芯、黑膜覆盖）进行对比试验。结果表明，3种栽培模式均优于常规种植，其中稻草包芯和黑膜覆盖栽培模式缩短了出苗时间，提高了商品薯率，增加了单株薯块数和单株薯块质量，显著提高了种植产量和效益，明显优于稻草免耕栽培模式，其中稻草包芯每667 m2纯收入比常规种植高出402.81元，产投比达1.76。     

Long-Term No-Tillage Direct Seeding Mode for Water-Saving and Drought-Resistance Rice Production in Rice-Rapeseed Rotation System

To study the effects of long-term no-tillage direct seeding mode on rice yield and the soil physiochemical property in a rice-rapeseed rotation system,a comparative experiment with a water-saving and drought-resistance rice(WDR)variety and a double low rapeseed variety as materials was conducted under no-tillage direct seeding(NTDS)mode and conventional tillage direct seeding(CTDS)mode for four years,using the CTDS mode as the control.Compared with the CTDS mode,the actual rice yield of WDR decreased by 8.10%at the first year,whereas the plant height,spikelet number per panicle,spikelet fertility,1000-grain weight,grain yield,actual yield,and harvest index increased with no-tillage years,which led to the actual yield increase by 6.49%at the fourth year.Correlation analysis showed that the panicle length was significantly related to the actual yield of WDR.Compared with the CTDS mode in terms of the soil properties,the pH value of the NTDS mode decreased every year,whereas the contents of soil organic matter and total N of the NTDS mode increased.In the 0–5 cm layer of the NTDS mode,the soil bulk decreased,whereas the contents of soil organic matter,total N,and available N increased.In the 5–20 cm layer of the NTDS mode,the available N and K decreased,whereas the soil bulk,contents of soil organic matter,and total N increased.In summary,the NTDS mode increased the rice yield,and could improve the paddy soil fertility of the top layer.     

东北平原棕壤土区合理耕层耕作模式与配套机具研究

目前,土地沙漠化面积增大,传统耕作机械田间作业频繁,增加了土壤坚实度,使土壤容重增加,造成了土壤的板结,犁底层加厚上移,影响作物产量、制约了农业生产的可持续发展。针对东北平原棕壤土区辽宁省铁岭县的实际情况,结合联合整地、深松、深松联合整地及免耕播种4种耕作模式,与当地农作物种植合作社合作,对4种模式的土壤理化性质进行测试。在距地表5、10、15cm土壤深度时,深松模式土壤温度高于联合耕整地模式1.6、1.5、1.1℃;免耕播种比联合耕整地模式的土壤温度分别高了2.8、2.2、1.9℃。土壤含水率方面,免耕播种含水率最高,在垄台、向阳面、向阴面分别比联合耕整地模式高6.9%、12.2%、15.2%;在土壤容重与土壤紧实度方面,深松模式在深度10~30cm范围内土壤容重低于未深松模式0.3g/cm3。根据土壤理化特性,运用线性规划方法对现有配套机具进行优化配备,并对配备后进行效益分析,得出深松覆盖模式的收益最高,达到1.29万元/hm~2;其次是免耕播种模式,达到1.25万元/hm~2;深松联合整地模式与联合整地模式分别为0.90万元/hm~2和0.74万元/hm~2。同时,提出了一种适合当地土壤性质的耕作模式与合理配套机具。