刈割、AM真菌和施磷对根箱栽培中柑橘和柱花草生长的影响

利用根箱栽培模拟果园生草栽培,以柑橘Citrus sinensis(L)Osbeck．cv．Luogangcheng和柱花草Stylosanthes gracilis H．B．K．cv．Graham来研究生草刈割、AM真菌和施磷在减轻养分竞争上的作用．结果表明,3种措施在不同程度上减轻了柱花草对柑橘生长的抑制效应,增加了柑橘的株高、叶片数和干质量;柱花草刈割的作用最明显,导致柱花草的根冠比急剧降低,表明刈割可能是通过抑制根系生长来减轻养分竞争．     

Evolution of marine fisheries management in China from 1949 to 2019: How did China get here and where does China go next?

China is the world’s biggest fishing nation and a major player in the global seafood trade. Its fisheries development can decisively influence the global seafood trade, food security and marine conservation. In recent years, significant changes have taken place in China’s fisheries management priorities, policies and regulations. In this paper, we review the evolving fisheries management practices in China to delineate changes in the management policies, methods and their performances from 1949 to 2019. We determined that the following issues impede the development, implementation and enforcement of fisheries policies and regulations, namely the large size of the fishing fleet, large and poorly organized fisheries population, the “hidden” fishing capacity, uniform management approaches that sometimes fail to account for local conditions, lack of clearly defined and allocated fishing rights, limited data quality and availability, insufficient fisheries monitoring programmes, absence of a robust scientific input framework and insufficient stakeholder involvement. Combining those problems with China’s current management initiatives, we propose recommendations for China’s future fisheries reforms. We hope this paper can inform China’s marine fisheries policies and provide valuable references for further researches related to China’s sustainable fisheries management.     

Changing rainfall patterns and farmers’ adaptation through soil water management practices in semi-arid eastern Kenya

There is limited documentation of soil and water management technologies that enhance adaptation to climate change in drylands of Kenya. Rainfall patterns were analyzed in the semi-arid Machakos and Makueni counties of eastern Kenya using historical data. A total of forty-three smallholder farmers implementing soil water management practices were sampled, and an estimate of the seasonal water budget for current crop and livestock production systems computed. Analysis of rainfall amounts and distribution shows increasing variability, with the average annual total amounts decreasing over the past 50 years. Furthermore, the number of rainy days within the March-April-May season that can support crop growth is gradually decreasing. These decreases are however not significant at P < 0.05. There were more seasons with low rainfall amounts compared to those with high rainfall amounts. All these subject the smallholder crop and livestock production system to limited soil moisture. Farmers address the risk by harnessing and utilizing green (rainfall stored in soil) and blue (rainfall collected into storage tanks) water technologies. The study found that farmers in these semi-arid counties practice fifteen diverse soil and water management interventions on their farms. The most popular practices are cut-off drains, retention ditches, terracing, run-off harvesting, and agroforestry. The estimated seasonal water budget indicates the need for integrated soil and water management interventions to address the crop and livestock production constraints.     

Soil Quality Assessment under Restorative Soil Management Practices in Soybean (Glycine Max) after Six Years in Semi-Arid Tropical Black Lands of Central India

Vertisol soils of central India are heavy in texture, with high clay content and low organic matter. These soils are prone to degradation and the soil loss is due to poor management practices including excessive tillage. Based on a long-term study conducted for improving the quality of these soils, it was found that management practice such as low tillage (LT) + 4 t ha^?1 compost + herbicide (Hb) recorded significantly higher organic carbon (OC) (6.22 g kg^?1) and available N (188.5 kg ha^?1) compared to conventional tillage (CT) + recommended fertilizer (RF) + off-season tillage (OT) + hand weeding (HW) (OC: 4.71 g kg^?1, available nitrogen (N) (159.3 kg ha^?1). Among the physical soil quality parameters, mean weight diameter (MWD) was significantly higher under LT + 4 t ha^?1 straw + Hb (0.59 mm). The practice of LT + 4 t ha^?1 straw + HW recorded significantly higher microbial biomass carbon (MBC) (388.8 μg g^?1). The order of key indicators and their contribution towards soil quality was as follows: OC (29%) >, MBC (27%) > available zinc (Zn) (22%) > MWD (9%) > available boron (B) (8%), > dehydrogenase activity (DHA) (5%). The order of the best treatment which maintained soil quality index (SQI) values reasonably good (>1.5) was as follows: LT + 4t ha^?1 compost + HW (1.65) > LT + 4 t ha^?1 compost +Hb (1.60) > LT + 4t ha^?1 straw + HW (1.50). Hence, these treatments could be recommended to the farmers for maintaining higher soil quality in Vertisols under soybean system. Correlation studies revealed stronger relationship between key indicators like OC (R² = 0.627), MBC (R² = 0.884), available Zn (R² = 0.739) and DHA (R² = 0.604) with Relative Soil Quality Index (RSQI). The results of the present study would be highly useful to the researchers, farmers and land managers.     

Soil Organic Carbon and Nitrogen Fractions under Different Land Uses and Tillage Practices

Many questions have surfaced regarding long-term impacts of land-use and cultivation system on soil carbon (C) sequestration. The experiment was conducted at Ohio Agricultural Research and Development Center. Only minor variations of soil organic carbon (SOC) and nitrogen (N) fractions with depth under plow tillage (PT). The SOC, total nitrogen (TN), microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) concentrations were higher under grassland and forestland in the top 0–15 cm depth than arable soils. No-tillage (NT) also increased SOC and N fractions concentrations in the surface soils than PT. Compared to arable, grass and forest could significantly improve proportions of MBC and MBN, and reduce proportions of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON). NT and forest also increased the ratio of SOC/TN, MBC/MBN, and DOC/DON. Overall, grass and forest provided more labile C and improved C sequestration than arable. So did NT under arable land-use.     

Comparing System of Wheat Intensification (SWI) with standard recommended practices in the northwestern plain zone of India

The practices of the System of Rice Intensification (SRI) methodology have been extended to wheat and various other crops with reported good results. To assess such reports with respect to wheat, an experiment was conducted at the Indian Agricultural Research Institute, New Delhi during 2011–2012 and 2012–2013. This experiment compared the performance of wheat under System of Wheat Intensification (SWI) and standard recommended practices (SRPs). In 2011–2012, the SWI yield of 7.93 t ha^?1 was 30% higher than for SRP in 2012–2013, climatically a less favorable year, hence SWI performed relatively better with a 46% yield advantage under climate stress. SWI produced 12.5% less in the stressful year, while the reduction for the SRPs ranged from 18% to 31%. Differences in yield attributes and root traits were also observed in favor of SWI. Available N, P, and K in the soil after harvesting was increased with SWI, whereas depletion in nutrients with the SRPs indicated the scope for SWI sustaining soil fertility. Higher yield compensated for higher SWI costs of cultivation. A net return of US$ 1383 ha^?1 was obtained with SWI, 35% more than the US$ 1020 ha^?1 from SRPs. Overall, SWI outperformed the SRPs in terms of yields, climate resilience, and economics.     

不同农作管理措施对东北地区农田土壤有机碳未来变化的模拟研究

【目的】研究与探索不同农作管理措施对东北农业土壤有机碳的影响,为东北地区高产高效低碳农业及可持续发展提供科学依据。【方法】不同农作管理措施能够影响土壤有机碳（soil organic carbon,SOC）的未来变化,该研究基于东北地区4个长期定位试验站点（黑龙江省哈尔滨站点、吉林省公主岭站点、吉林省德惠站点、辽宁省沈阳站点）的试验数据,用站点的实测作物产量和SOC双标准对DAYCENT模型进行校验。DAYCENT模型调整的相关参数包括作物参数、耕作方式参数、施肥参数、收获参数和有机肥参数等,在对所选试验站点的长期定位试验结果校验后,利用已校验的各项参数,对模型模拟情况进行验证,发现模型模拟值与实测值吻合良好,表明DAYCENT模型适用于这4个地区的作物产量和SOC模拟,可以较好地模拟SOC的动态变化。进而研究在未来气候变化情景下（representative concentration pathway 4.5,RCP 4.5）,用校验了的DAYCENT模型对这4个站点在4种不同管理情景（施用化肥、增施有机肥、秸秆还田、免耕）下的SOC变化情况进行模拟。【结果】模拟结果显示,对于哈尔滨站点,采用有机肥和氮磷钾化肥配施处理（MNPK）在短时间内使SOC升高较快,而从长远来看,配施低量有机肥与单施用化肥对SOC增加的斜率基本一致,但由于化肥和有机肥配施（MNPK）处理的初始SOC含量高,其SOC未来含量的绝对值也比较高;对于德惠站点,虽然短时间内,免耕处理SOC低于常耕处理,但长期看来,免耕更有利于增加SOC,其SOC涨幅逐渐高于常耕处理,40年间相对增加了11.88%;公主岭站点有机肥氮磷钾化肥配施和氮磷钾化肥结合秸秆还田措施较单施化肥可显著提高农田SOC;沈阳站点的未来有机碳模拟发现,在单施化肥情况下,未来的42年内SOC呈略微下降趋势,相对降低2.83%,从长远看来,单施化肥并不能使该地区SOC增加,因此,可以考虑采用有机肥和氮磷钾化肥配施等措施来提高该地区的农田SOC。【结论】DAYCENT模型可以有效地模拟作物产量和土壤有机碳的动态变化,模型适应性较强,同时DAYCENT模型可用于模拟站点未来SOC的动态变化。在东北地区农田土壤管理方面,可通过合理的有机肥化肥配施、推广免耕和秸秆还田技术来固定土壤碳,最终达到提高土壤有机碳库和促进农业可持续发展的目标。     

土传病害生物防治研究进展

土传病害已成为严重制约我国农牧业发展的主要原因,近年来人们对于食物安全的重视和环保意识的增强,对农业的可持续发展提出了更高的要求。生物防治因其低成本、高效率、环境友好和无药物残留等特点已成为当前国内外植物病害防治的研究热点。本文从农艺措施改良和优化,利用细菌、真菌、放线菌等生防微生物进行生物防治,诱导寄主产生系统抗病性和其他生物防治方法等几个方面对国内外植物土传病害生物防治的研究现状进行了综述,提出了生物防治目前存在的问题,并对生物防治的研究进行了展望。     

Microclimate and CO2 fluxes on continuous fine days in the Xihu desert wetland,China

The Xihu desert wetland is located in an extremely arid area in Dunhuang,Gansu province of Northwest China.The area is home to an unusual geographic and ecological environment that is considered unique,both in China and the world.Microclimate is not only related to topography,but is also affected by the physical properties of underlying ground surfaces.Microclimate and CO2 flux have different characteristics under different underlying surface conditions.However,until now,few studies have investigated the microclimate characteristics and CO2 flux in this area.The eddy covariance technique(ECT) is a widely used and effective method for studying such factors in different ecosystems.Basing on data from continuous fine days obtained in the Dunhuang Xihu desert wetland between September 2012 and September 2013,this paper discussed and compared the characteristics of daily microclimate variations and CO2 fluxes between the two periods.Results from both years showed that there was a level of turbulent mixing and updraft in the area,and that the turbulent momentum flux was controlled by wind shear under good weather conditions.The horizontal wind velocity,friction wind velocity and vertical wind velocity were commendably consistent with each other.Air temperature in the surface layer followed an initial decreasing trend,followed by an increasing then decreasing trend under similar net radiation conditions.With changes in air temperature,the soil temperature in the surface layer follows a more obvious sinusoidal fluctuation than that in the subsoil.Components of ground surface radiation during the two study periods showed typical diurnal variations.The maximum diurnal absorption of CO2 occurred at around 11:00(Beijing time) in the Xihu desert wetland,and the concentrations of CO2 in both periods gradually decreased with time.This area was therefore considered to act as a carbon sink during the two observation periods.     

Effects of cotton field management practices on soil CO2 emission and C balance in an arid region of Northwest China

Changes in both soil organic C storage and soil respiration in farmland ecosystems may affect atmospheric CO2 concentration and global C cycle. The objective of this field experiment was to study the effects of three crop field management practices on soil CO2 emission and C balance in a cotton field in an arid region of Northwest China. The three management practices were irrigation methods（drip and flood）, stubble managements（stubble-incorporated and stubble-removed） and fertilizer amendments（no fertilizer（CK）, chicken manure（OM）, inorganic N, P and K fertilizer（NPK）, and inorganic fertilizer plus chicken manure（NPK＋OM））. The results showed that within the C pool range, soil CO2 emission during the whole growing season was higher in the drip irrigation treatment than in the corresponding flood irrigation treatment, while soil organic C concentration was larger in the flood irrigation treatment than in the corresponding drip irrigation treatment. Furthermore, soil CO2 emission and organic C concentration were all higher in the stubble-incorporated treatment than in the corresponding stubble-removed treatment, and larger in the NPK＋OM treatment than in the other three fertilizer amendments within the C pool range. The combination of flood irrigation, stubble incorporation and application of either NPK＋OM or OM increased soil organic C concentration in the 0-60 cm soil depth. Calculation of net ecosystem productivity（NEP） under different management practices indicated that the combination of drip irrigation, stubble incorporation and NPK＋OM increased the size of the C pool most, followed by the combination of drip irrigation, stubble incorporation and NPK. In conclusion, management practices have significant impacts on soil CO2 emission, organic C concentration and C balance in cotton fields. Consequently, appropriate management practices, such as the combination of drip irrigation, stubble incorporation, and either NPK＋OM or NPK could increase soil C storage in cotton fie