Effect of soil management on soil erosion on sloping farmland during crop growth stages under a large-scale rainfall simulation experiment

Soil erosion on farmland is a critical environmental issue and the main source of sediment in the Yellow River, China. Thus, great efforts have been made to reduce runoff and soil loss by restoring vegetation on abandoned farmland. However, few studies have investigated runoff and soil loss from sloping farmland during crop growth season. The objective of this study was to investigate the effects of soil management on runoff and soil loss on sloping farmland during crop growth season. We tested different soybean growth stages (i.e., seedling stage (R1), initial blossoming stage (R2), full flowering stage (R3), pod bearing stage (R4), and initial filling stage (R5)) and soil management practice (one plot applied hoeing tillage (HT) before each rainfall event, whereas the other received no treatment (NH)) by applying simulated rainfall at an intensity of 80 mm/h. Results showed that runoff and soil loss both decreased and infiltration amount increased in successive soybean growth stages under both treatments. Compared with NH plot, there was less runoff and higher infiltration amount from HT plot. However, soil loss from HT plot was larger than that from NH plot in R1–R3, but lower in R4 and R5. In the early growth stages, hoeing tillage was effective for reducing runoff and enhancing rainfall infiltration. By contrast, hoeing tillage enhanced soil and water conservation during the late growth stages. The total soil loss from HT plot (509.0 g/m2) was 11.1% higher than that from NH plot (457.9 g/m2) in R1–R5. However, the infiltration amount from HT plot (313.9 mm) was 18.4% higher than that from NH plot (265.0 mm) and the total runoff volume from HT plot was 49.7% less than that from NH plot. These results indicated that crop vegetation can also act as a type of vegetation cover and play an important role on sloping farmland. Thus, adopting rational soil management in crop planting on sloping farmland can effectively reduce runoff and soil loss, as well as maximize rainwater infiltration during crop growth period.

美国卡罗莱纳州南部海岸地区火炬松立地质量评价(英文)

利用常规土壤调查方法辨认和描述了11种土壤类型,以便分析火炬松(Pinus taeda L.)的生产力。每个土壤类型建立4个4公顷的研究地点(每个研究地点包含4个测量样地)上。利用逐步多元回归分析土壤母质层(结合下层土壤质地和地质学)和排灌级别,它们是立地指标(树龄25年)重要的预测值,整个线性回归模型的相关系数(R2)为0.55。在Wicomico-Penholoway地区的肥沃下层土与Pamlico-Princess Anne地区的黏土的土壤母质层立地指标最大相差3.9m。排灌级别的立地指标最大相差0.7m。例如,排灌差的土壤的立地指标比稍差的低0.7m。11个土壤类型中的7个土壤类型,80%以上估计的平均立地指标与实际的土壤类型平均立地指标相差±0.8m。其它4个土壤类型(标号:G,I,C和K)需要重新定义或更多地集中采样。为了精确的定性立地质量,需要对其中两个土壤类型(基于地质学的土壤类型G和基于土壤排灌级别土壤类型I)进行重新划分。土壤排灌级别的变化和上层土壤被转化为干草列的变化数量是两个影响土壤类型(C)立地质量的影响因子。第4个土壤类型K立地指标数据有很大的变化,部分原因是由于采样地点和个别测量样地的优良垫层和人工排灌设施较少。具有不同排灌级别的土壤母质层(结合下层土壤质地和地质学)是重要的卡罗莱纳州南部海岸地区的立地质量的影响因子。

Effect of Tillage and Residue Retention on Soil Properties and Crop Yields in Wheat-Mungbean-Rice Crop Rotation under Subtropical Humid Climate

The effects of conservation agriculture (CA) practices on soil properties along with crop yields of rice-based triple cropping systems have not been adequately assessed in Bangladesh. An experiment was conducted at Bangladesh Agricultural Research Institute, Gazipur, Bangladesh from 2009 to 2012 to assess the effects of tillage practices and crop residue retention on soil physical properties, soil organic carbon (SOC) and crop yields in a wheat-mungbean-rice system. Treatments consisted of three tillage practices (MT: minimum tillage;CT: conventional tillage and DT: deep tillage) and eight levels of crop residue management (S0—no residues retention, Sr—retention of 30 cm rice straw, Sm—whole mungbean stover retention, SW—30 cm wheat straw retention, Smr—whole mungbean stover & 30 cm rice straw retention, Srw—30 cm rice & wheat straw retention, Smw—whole mungbean stover & 30 cm wheat straw retention and Swrm—30 cm wheat and rice straw along with whole mungbean stover retention) were applied in split plot design with three replications. Bulk density (BD) and porosity responded positively to MT and increased residue retention of all crops (p > 0.05). Minimum tillage and Swrm also significantly accumulated SOC (p < 0.05;0.38% higher than DT with no residue retention) and retained soil moisture (p < 0.05). Minimum tillage practice performed better in upland crops (p < 0.05;wheat & mungbean yields) and CT outperformed MT in wetland rice crop (p < 0.05). The grain and straw yields of wheat and rice were also influenced by previous crop residue retentions (p < 0.05). The results, therefore, suggested that increased residue retention with minimum tillage practices improved soil properties and yield of upland crops but with deeper tillage practices consistently maintained wetland rice production.

Spatiotemporal variation and evaluation of agriculture green development: a case study of Hainan Province, China

The realization of green and sustainable development of agriculture is the common pursuit all over the world. Agriculture green development(AGD)program has been proposed as a sustainable development strategy in China,but insufficient is known about the quantitative evaluation of spatiotemporal variation in AGD at the regional scale. This study aimed to assess spatiotemporal patterns in AGD at the county/city-based regional level. For this purpose, a systematic index evaluation system was developed to assess the performance of socioeconomic, food production and environmental components in a key economic region(Hainan Province) of China. Hainan improved its AGD index(representing the overall performance toward achieving AGD) from 38.8 in 1988 to 40.9 in 2019. The socioeconomic development and agricultural productivity have improved with time;environmental quality declined due to overuse of chemicals from 1988 to 2013, but steadily improved after 2013, indicating positive effects of reducing chemical input. There was a higher AGD index in the coastal vs. central regions and the southern vs. northern regions. Scenarios featuring improved nutrient management or optimized diet structure and reduced waste improved economic benefits and social productivity while concurrently reducing environmental degradation. These results provide new insights for the future development of green and sustainable agriculture and formulation of agricultural policies in Hainan Province of China and even other developing countries that are facing or will soon face similar challenges.

Emerging pollutants in the environment:A challenge for water resource management

A significant number of emerging pollutants(EPs)resulting from point and diffuse pollution is present in the aquatic environment.These are chemicals that are not commonly monitored but have the potential to enter the environment and cause adverse ecological and human health effects.According to the NORMAN network,at least 700 substances categorized into 20 classes,have been identified in the European aquatic environment.In light of their potential impact action is urgently required.In this study,we present a concept that shows the current state of art and challenges for monitoring programs,fate and risk assessment tools and requirements for policies with respect to emerging pollutants as a base for sustainable water resource management.Currently,methods for sampling and analysis are not harmonized,being typically focused on certain EP classes.For a number of known highly hazardous EPs detection limits are too high to allow proper risk assessment.For other EPs such as microplastics method development is in its infancy.Advanced ultra-sensitive instrumental techniques should be used for quantitative determination of prioritized EPs in water,suspended matter,soil and biota.Data on EPs'and their metabolites'properties that determine their fate in the environment are often not available.National surveys on water quality often use different parameters for water quality assessment and often do not include EPs.A harmonized monitoring of surface and groundwater is not yet achieved and urgently required.Specific component integrated into models assessing the fate of EPs in a multi compartment environmental approach are missing and must be developed.The main goal of risk assessment is the overall protection of ecological communities in the aquatic environment and human health.New methods for assessing the cumulative risks from combined exposures to several stressors,including mixtures of EPs in a multi-scale approach are required.A combination of regulations and management measures with respect to use/emissions of EPs into the environment,as well as to their occurrence in the environment are fundamental to reach an efficient water resource management.

Modelling the role of ground-true riparian vegetation for providing regulating services in a Mediterranean watershed

Intensive agricultural and industrial activities are often considered major sources of water contamina-tion.Currently,riparian vegetation(RV)is increasingly being promoted as a solution to balance the potentially adverse effects that agriculture may have on water quality.Nonetheless,existing RV is often overlook in recent modelling efforts,failing to capture the current amount of ecosystem services provide.Here,we used the Soil and Water Assessment Tool ecohydrological model to simulate the influence of ground-true RV on i)nutrient(nitrate and total phosphorus)and sediment exports from agricultural areas and ii)its effect for in-stream concentrations.These results are further compared against a set of hypothetical scenarios of different RV widths and different land-uses.Our results point to a great rele-vance of existing RV in controlling in-stream concentration of sediments and nutrients where pressure from agriculture is highest,preventing them to surpass limits set in the EU Water Framework Directive.On the other hand,in areas with industry discharges,the role of RV is limited and model results suggest that restoring RV would have limited impacts.We illustrate how existing RV may already provide strong but not acknowledged water quality regulation services,how these services can differ substantially between nearby streams,and that effective strategies to improve water quality using RV must acknowledge existing patterns of vegetation,land use and contamination sources.

Quality of terrestrial data derived from UAV photogrammetry:A case study of Hetao irrigation district in northern China

Most crops in northern China are irrigated,but the topography affects the water use,soil erosion,runoff and yields.Technologies for collecting high-resolution topographic data are essential for adequately assessing these effects.Ground surveys and techniques of light detection and ranging have good accuracy,but data acquisition can be time-consuming and expensive for large catchments.Recent rapid technological development has provided new,flexible,high-resolution methods for collecting topographic data,such as photogrammetry using unmanned aerial vehicles(UAVs).The accuracy of UAV photogrammetry for generating high-resolution Digital Elevation Model(DEM)and for determining the width of irrigation channels,however,has not been assessed.A fixed-wing UAV was used for collecting high-resolution(0.15 m)topographic data for the Hetao irrigation district,the third largest irrigation district in China.112 ground checkpoints(GCPs)were surveyed by using a real-time kinematic global positioning system to evaluate the accuracy of the DEMs and channel widths.A comparison of manually measured channel widths with the widths derived from the DEMs indicated that the DEM-derived widths had vertical and horizontal root mean square errors of 13.0 and 7.9 cm,respectively.UAV photogrammetric data can thus be used for land surveying,digital mapping,calculating channel capacity,monitoring crops,and predicting yields,with the advantages of economy,speed and ease.

Identification of suitable sites for rainwater harvesting structures in arid and semi-arid regions:A review

Harvested rainwater is an alternative source of water in arid and semi-arid regions(ASARs)around the world.Many researchers have developed and applied various methodologies and criteria to identify suitable sites and techniques for rainwater harvesting(RWH).Determining the best method or guidelines for site selection,however,is difficult.The main objective of this study was to define a general method for selecting suitable RWH sites in ASARs by assembling an inventory of the main methods and criteria developed during the last three decades.We categorised and compared four main methodologies of site selection from 48 studies published in scientific journals,reports of international organisations,or sources of information obtained from practitioners.We then identified three main sets of criteria for selecting RWH locations and the main characteristics of the most common RWH techniques used in ASARs.The methods were diverse,ranging from those based only on biophysical criteria to more integrated approaches including socio-economic criteria,especially after 2000.The most important criteria for the selection of suitable sites for RWH were slope,land use/cover,soil type,rainfall,distance to settlements/streams,and cost.The success rate of RWH projects tended to increase when these criteria were considered,but an objective evaluation of these selection methods is still lacking.Most studies now select RHW sites using geographic information systems in combination with hydrological models and multi-criteria analysis.

Remote sensing vs.field-based monitoring of agricultural terrace degradation

The degradation of agricultural terraces is considered a major challenge to soil and water conservation in steep-slope viticulture.Although terracing is a widespread conservation practice,its sustainability is threatened by adverse climatic and man-made conditions.Previous studies have shown the impact of terrace designs on the formation of runoff pathways,causing degradation processes on terrace platforms(e.g.sheet erosion)and walls(e.g.piping,landslides,collapse).This study evaluates a remote sensing versus a field-based approach to monitor hydrological processes responsible for terrace degradation,as tested in a north-Italian vineyard.The field-based approach was based on spatially measured Soil Moisture Content(SMC)using a Time Domain Reflectometry(TDR)instrument,which clearly revealed saturation hotspots around two damaged terraces in the study area.Moreover,these zones showed a particular cross-sectional SMC profile,with the highest saturation close to the terrace platform edges.The remote sensing approach was based on aerial imagery acquired by an Unmanned Aerial Vehicle(UAV)and photogrammetric reconstruction of the vineyard geomorphology,allowing terrain-based analysis and physical erosion modelling.In this approach,simulations indicated that terrace damages could be partly explained by the formation of preferential runoff pathways caused by the terrace design.This parallel methodology allowed a comparison of the merits and limitations of either approach,as done in light of published work.The occurrence of two SMC hotspots at terrace edges(and their non-typical cross-sectional profiles)could be better understood from simulated surface flow paths.While the causal relationship between heterogeneous soil saturation and terrace instability has been previously reported in literature,the novelty of the presented study is the use of topsoil SMC as an indicator of potential damages,favouring the scalability compared to fixed,local and often intrusive terrace sub-surface ex-periments.Remote sensing based approaches,however,tend to offer the most time-efficient solution on larger scales,and aerial acquisition of SMC distribution could thus potentially offer a powerful integrated methodology.

A GIS-based approach for identifying potential sites for harvesting rainwater in the Western Desert of Iraq

People living in arid and semi-arid areas with highly variable rainfall and unforeseeable periods of droughts or floods are severely affected by water shortages and often have insecure livelihoods. The construction of dams in wadies to harvest rainwater from small watersheds and to induce artificial groundwater recharge is one of the solutions available to overcome water shortages in the Western Desert of Iraq. The success of rainwater harvesting (RWH) systems depends heavily on their technical design and on the identification of suitable sites. Our main goal was to identify suitable sites for dams using a suitability model created with ModelBuilder in ArcGIS 10.2. The model combined various biophysical factors: slope, runoff depth, land use, soil texture, and stream order. The suitability map should be useful to hydrologists, decision-makers, and planners for quickly identifying areas with the highest potential for harvesting rainwater. The implementation of this method should also support any policy shifts towards the widespread adoption of RWH.