Impact on soil physical properties of using large-grain legumes for catch crop cultivation under different tillage conditions

In Central Europe, various plant species including large-grain legumes and their mixtures are grown as catch crops, particularly between grains harvested early and subsequent summer crops. This article investigates the question of how soil structure in the topsoil is influenced when catch cropping with large-grain legumes (experimental factor A: without catch crop, with catch crop) under different ploughless tillage conditions during catch crop seeding (experimental factor B: deep tillage/25–30 cm, shallow tillage/8–10 cm). Five one-year trials were performed using standard machinery at various sites in Germany. Soil core samples extracted from the topsoil in the spring after catch crop cultivation served to identify air capacity, saturated hydraulic conductivity and precompression stress. The above-ground and below-ground biomass yields of the catch crops were also determined at most of the sites. In addition, the soil compaction risk for the working steps in the experiments was calculated using the REPRO model.The dry matter yield of the catch crops varied considerably between the individual trial sites and years. In particular, high levels of dry matter were able to form in the case of early seeding and a sufficient supply of precipitation. The soil structure was only rarely affected positively by catch crop cultivation, and catch crops did not contribute in the short term to loosening already compacted topsoils. In contrast, mechanical soil stresses caused by driving over the ground and additional working steps used in cultivating catch crops often led to lower air capacity in these treatments. This is consistent with the soil compaction risks calculated using the REPRO model, which were higher in the treatments with catch cropping. Catch crop cultivation also only resulted in improved mechanical stability at one location. The positive effect of deep ploughless tillage on air capacity and saturated hydraulic conductivity, however, became more clearly evident regardless of catch crop cultivation. In order for catch crop cultivation with large-grain legumes to be able to have a favourable impact on soil structure, it is therefore important that cultivating them does not result in any new soil compaction. In the conditions evaluated, deep tillage was more effective at loosening compacted topsoil than growing catch crops.     

土壤肥料学云南省省级精品课程教学改革与实践

为适应高等农业教育改革和推进素质教育的要求,针对云南农业大学涉农专业的基本特点,结合土壤肥料学云南省省级精品课程的建设和云南省土壤与肥料方面的基本情况,以培养学生的创新精神与实践能力为根本目的,在教学内容、教学条件、教学方法等方面进行了该课程教学改革与实践,收到显著成效.     

绿洲膜下滴灌调亏对马铃薯土壤环境及产量的影响

为测定膜下滴灌调亏马铃薯全生育期内不同调亏水平土壤养分、土壤水热动态、生长动态、产量效应和水分利用效率,于2016年在河西荒漠绿洲灌区民乐县益民灌溉试验站开展了马铃薯不同生育阶段水分调亏灌溉的试验研究,结果表明,马铃薯膜下滴灌调亏土壤水热变化均匀且利用率高,有利于马铃薯对土壤养分的充分吸收和利用;土壤养分是土壤肥力的核心,是植物在生长发育过程中不可或缺的重要因素,膜下滴灌调亏栽培能有效减少土壤速效养分的流失,并提高马铃薯对土壤速效养分的利用效率;不同生育阶段马铃薯耗水量受水分调亏程度影响较大,其耗水量随调亏程度增大而显著减少(P0.05),水分调亏处理马铃薯全生育期总耗水量均低于全生育期充分灌水CK处理。块茎形成期轻度水分亏缺马铃薯水分利用效率、灌溉水利用效率、生物量均达到最大,较全生育期充分灌水显著提高29.04%,35.61%。因此,块茎形成期轻度水分亏缺灌溉方式能使马铃薯根区土壤始终保持湿润状态,有效减少渗漏损失和植株间无效蒸发损失,改善土壤水、肥和热量状况,有利于提高作物水分利用效率,且不显著降低马铃薯最终产量。     

免耕和稻草还田对稻田土壤肥力和水稻产量的影响

为了明确稻草还田和免耕等保护性耕作措施对土壤肥力和水稻产量的影响,自2008年于广西大学农学院科研基地进行长期定位试验,设置免耕（NT）、免耕+稻草覆盖还田（NT-SMR）、常规耕作+稻草覆盖还田（CT-SMR）、常规耕作（CT）和常规耕作+稻草翻压还田（CT-SR）5个处理,于2018年水稻成熟期测定产量,水稻收获后分层（0~5、5~10和10~20cm）测定土壤肥力。结果表明,稻田不同土层肥力指标均存在显著性差异,总体上表现为0~5、5~10和10~20cm土层的有机碳、全氮、碱解氮、有效磷和速效钾含量依次下降。NT-SMR处理显著提高了0~5cm土层的有机碳、全氮、碱解氮和有效磷含量,但降低了土壤速效钾含量。在5~10和10~20cm土层,稻草还田处理的有机碳、全氮、碱解氮、有效磷和速效钾含量均优于无稻草还田处理。水稻产量与土壤肥力呈显著正相关。2016年CT-SR处理水稻产量在早季分别比NT和CT处理显著提高了8.52%和7.99%,在晚季分别显著提高了12.12%和7.55%;2018年NT-SMR处理的水稻产量在早季分别比NT和CT处理显著提高了17.78%和10.30%,在晚季分别显著提高了13.88%和19.39%。因此,免耕和稻草还田能明显提高稻田耕作层土壤肥力,增加稻谷产量。     

黄河故道区域不同种植模式及秸秆还田方式对土壤的改良效果

由于长期受到流水冲击,黄河故道区域农田以中低产田为主,因此本区域农田质量提升成为黄河中下游平原绿色发展的重要研究课题。在河南濮阳清丰地区秸秆还田方式的基础上,选取黄河故道区域广泛种植的小麦、玉米和花生三大主要农作物,于2009年进行4种种植模式长期定位试验：小麦-玉米、小麦-花生、小麦-玉米-小麦-花生和单季花生,其中小麦和玉米秸秆全部还田,花生秸秆不还田,探究不同种植模式对土壤理化性质和微生物群落结构的影响。结果表明,秸秆还田量越多,土壤有机质含量提高越多,小麦-花生、小麦-玉米-小麦-花生种植模式下土壤有机质含量最高,且其土壤含水量也显著高于其他处理,上层土壤容重有所降低,显著改善了土壤砂质化,提升了土壤的蓄水能力;秸秆还田量较大的种植模式的养分保持能力明显提高,养分含量显著增加;微生物群落结构对不同种植模式响应结果为,花生可以显著提升微生物丰度,微生物群落多样性随种植作物类型的增加而增加。因此,小麦-玉米-小麦-花生种植模式较为适宜濮阳清丰黄河故道区域,有利于土壤改良和区域农业的可持续发展。     

Organic farming fosters agroecosystem functioning in Argentinian temperate soils: Evidence from litter decomposition and soil fauna

Benefits of organic farming on soil fauna have been widely observed and this has led to consider organic farming as a potential approach to reduce the environmental impact of conventional agriculture. However, there is still little evidence from field conditions about direct benefits of organic agriculture on soil ecosystem functioning. Hence, the aims of this study were to compare the effect of organic farming versus conventional farming on litter decomposition and to study how this process is affected by soil meso- and macrofauna abundances. Systems studied were: (1) organic farming with conventional tillage (ORG), (2) conventional farming with conventional tillage (CT), (3) conventional farming under no-tillage (NT), and (4) natural grassland as control system (GR). Decomposition was determined under field conditions by measuring weight loss in litterbags. Soil meso- and macrofauna contribution on decomposition was evaluated both by different mesh sizes and by assessing their abundances in the soil. Litter decomposition was always significantly higher after 9 and 12 months in ORG than in CT and NT (from 2 to 5 times in average), regardless decomposer community composition and litter type. Besides, mesofauna, macrofauna and earthworm abundances were significantly higher in ORG than in NT and CT (from 1.6 to 3.8, 1.7 to 2.3 and 16 to 25 times in average, respectively for each group). These results are especially relevant firstly because the positive effect of ORG in a key soil process has been proved under field conditions, being the first direct evidence that organic farming enhances the decomposition process. And secondly because the extensive organic system analyzed here did not include several practices which have been recognized as particularly positive for soil biota (e.g. manure use, low tillage intensity and high crop diversity). So, this research suggests that even when those practices are not applied, the non-use of agrochemicals is enough to produce positive changes in soil fauna and so in decomposition dynamics. Therefore, the adoption of organic system in an extensive way can also be suggested to farmers in order to improve ecosystem functioning and consequently to achieve better soil conditions for crop production.     

Impact of soil engineering by two contrasting species of earthworms on their dispersal rates

By burrowing galleries and producing casts, earthworms are constantly changing the structure and properties of the soils in which they are living. These changes modify the costs and benefits for earthworms to stay in the environment they modify. In this paper, we measured experimentally how dispersal behaviour of endogeic and anecic earthworms responds to the cumulative changes they made in soil characteristics. The influence of earthworm activities on dispersal was studied in standardised mesocosms by comparing the influence of soils modified or not modified by earthworm activities on earthworm dispersal rates.The cumulative use of the soil by the earthworms strongly modified soil physical properties. The height of the soil decreased over time and the amount of aggregates smaller than 2 mm decreased in contrast to aggregates larger than 5 mm that increased. We found that: (i) earthworm activities significantly modified soil physical properties (such as bulk density, soil strength and soil aggregation) and decreased significantly the dispersal rates of the endogeic species, whatever the species that modified the soil; (ii) the decreasing in the dispersal proportion of the endogeic species suggests that the cost of engineering activities may be higher than the one of dispersal; (iii) the dispersal of the anecic species appeared to be not influenced by its own activities (intra-specific influences) or by the activities of the endogeic species (inter-specific influences). Overall these results suggest that the endogeic species is involved in a process of niche construction, which evolved jointly with its dispersal strategy.     

土壤中根皮苷和根皮素对桃幼苗的影响

以一年生桃嫁接苗为试材,在盆栽条件下研究了苹果园土壤中特征酚酸类物质——根皮苷和根皮素对桃苗生物量、根系活力、根系保护性酶活性和MDA含量的影响。结果表明,根皮苷对桃幼苗的伤害显著,与对照相比,鲜质量、干质量分别降低了16.66%和21.58%,根系活力降低了33.04%,SOD、POD活性分别降低了40.80%和31.10%,MDA含量提高了116.34%。根皮素对桃苗的影响不大。高锰酸钾处理明显缓解了根皮苷对桃苗的伤害,苹果园土壤中的根皮苷含量降低了57.80%,提高了桃苗的生物量、根系活力和保护性酶活性,降低了MDA含量。综上,老龄苹果园土壤实测含量的根皮苷(0.343mg·kg~(-1))可降低桃苗的生物量,适量的高锰酸钾能缓解根皮苷的伤害作用。     

河北省土壤有机质时空变化分析

采用BP神经网络和地统计方法,对1980~2009年间河北省耕地土壤有机质时空变化规律及影响因素进行对比分析。结果表明:河北省耕地土壤有机质具有西北高东南低的格局;随着时间的推移,有机质总体呈现上升趋势。1980年的低值区域到了2009年SOM上升变化明显,成为热点;北部坝上、西部太行山区及东部沿海地区到2009年SOM含量下降,成为冷点。分析表明,这种变化格局的形成与施用有机肥、实施秸秆还田等社会经济过程有关。本研究为预测有机质变化趋势、改善土壤质量、优化种植结构和耕地的可持续发展提供了一定依据。     

The Relationship Between Vegetation Characteristics and Altitudes in Transitional Permafrost Zone in Xidatan,Qinghai-Tibetan Plateau

Many studies showed that permafrost has profound influence on alpine ecosystem. However, former researches were mainly focused on typical points by temporal scales. There were few studies about the correlation between vegetation characteristics and different altitudes covering a large region in spatial pattern, especially in transitional permafrost(TP). There were continuous permafrost(CP) discontinuous permafrost(DCP) and seasonal frozen ground(SFG) in this study region. The types of permafrost changed from SFG to DCP, and finally become CP as the altitudes of Xidatan increase. In this paper, 112 845 points interpreted by HJ1-B(environment and disaster monitoring and prediction small satellite constellation), vegetation investigation points, thawing layer thickness research sites, ground temperature and water content observation plots were used to examine the spatial pattern of vegetation which were located in different altitudes in Xidatan, a typical TP region, in Qinghai-Tibetan Plateau. Vegetation characteristics, soil moisture content(SMC) and thaw depths were collected in 15 August to 25 August2012. Characteristics of vegetation were mainly represented by fractional vegetation cover(FVC) derived from the normalized difference vegetation index(NDVI), as well as above ground biomass(AGB). In this paper, we analyzed that the distinction of vegetation characteristics in each range through statistics data. These ranges were divided by varied altitudes. For examples, the ranges were divided into 50 m or 100 m. In this study we use a large area plots method to further discuss the relationship between the features of vegetation and the different regions of permafrost based on altitudes shifts in Xidatan. A diagram described the vegetation characteristics variability with rising altitudes in transitional permafrost region was drawn in this paper. Our results illustrated the FVCs first increased in SFG region and then decreased in DCP zone slowly, and in CP region FVCs soared then dropped dramatically. With the altitudes increased, the curve of FVCs indicated a parabolic distribution except a little difference in the first 200 m range.