N_2O emissions from agricultural soils in the North China Plain: the effect of chemical nitrogen fertilizer and organic manure

An enclosed chamber technique was used to measure N 2O emissions from intensively agricultural soils of the North China Plain during the periods of 1995—1996 and 1997—1998, to reflect distinct components of winter wheat and summer maize growing seasons. The results showed that the continuous application of fertilizer in agricultural soils increased N\-2O emissions by a factor of 24.1—28.1, the calculated annual chemical N fertilizer\|transformed N\-2O\|N emissions was 0.67%. Our results indicated that the application of organic manure also had a significant influence on soil N 2O emissions, which combined with the use of chemical N increased about 20% in a year. It was calculated that there were about 0.11% N of organic manure transformed as N 2O N. Annual mean N 2O emission from our study area of fertilized soils was estimated to be 57.1 μgN 2O/(m 2·h). A weak correlation was also found between N 2O emissions and soil available nitrogen content NH + 4.

Chemicals,Energy,and Biomaterials from Agricultural Waste Resources in South China

Owing to its subtropical or tropical environment and climate,South China is home to unique agricultural crops such as sugar cane,pineapple,banana,cassava,and rice,which generate a large amount of lignocellulosic agricultural wastes during agricultural as well as associated industrial processing.The efficient utilization of these wastes will have a significant impact on the economy and sustainable development of South China.This paper reviews the research investigations conducted both in China and elsewhere on the conversion of wastes from these subtropical or tropical agricultural crops into useful chemicals,energy,and biomaterials.The goal of this paper is to promote and summarize the extensive investigations on these agricultural wastes for the development of biorefinery.

How United States Agricultural Herbicides Became Military and Environmental Chemical Weapons: Historical and Residual Effects

Discoveries in Charles Darwin’s laboratory led to modern herbicides. Darwin discovered the internal mechanism that directed plants to grow toward sunlight and sources of water. Scientists in Europe and America later called this mechanism a plant’s hormone response system. Administrators and scientists, including Dr. Ezra J. Kraus, the Head of the Botany Department at the University of Chicago and a plant physiologist, suggested on the eve of WWII that weed killers had significant military value as chemical weapons. Dr. Kraus obtained access to a synthetic chemical, 2,4-D, and found that when the chemical was absorbed through the leaves of plants, it destroyed a plant’s hormones. After exposure, the plant experienced rapid and uncontrolled growth, and then the leaves shriveled, died and fell off. Dr. Kraus obtained funding for his Department of Botany research program from Department of Defense (DOD) during World War II (WWII). Camp Detrick (Biological Weapons Laboratory) scientists later obtained samples of newly created 2,4,5-T which contained unknown amounts of the by-product dioxin TCDD. In the 1950s and 1960s, Fort Detrick military scientists formulated the herbicide Agent Orange, which was a 50 - 50 mixture of 2,4-D and 2,4,5-T. These dual purpose herbicides were used by DOD and USDA. American and European farmers in the 1940s used 2,4-D and 2,4,5-T to eliminate weeds from pastureland and cropland. After WWII, synthetic herbicides (and pesticides) development continued in tandem with production of synthetic fertilizers and breeding of high-yield plant varieties. These new agricultural products were then shipped worldwide to increase crop yields, as part of the Green Revolution. This new system of agricultural technologies was intended to eliminate global starvation and increase food security by increasing field and farm crop yields. In contrast, the goal of military use of herbicides, as chemical weapons, was to defoliate jungle forests and destroy food crops as a strategy to win battles and wars. The primary objective of this research study is to describe how agricultural herbicides became tactical chemical weapons. A current assessment will address the environmental impacts of military and environmental chemical weapons on the United States and Vietnam ecosystems and need for additional dioxin TCDD hotspot clean-up efforts.

Removal of heavy metals from sewage sludge by low costing chemical method and recycling in agriculture

Experiments were carried out to study the removal of heavy metals from municipal sewage sludge by proper method for land application. The sequential extractions for metal fractionation showed that the non digested sludge from Guangzhou contained Cu and Zn principally bound to carbonate and oxides and the metal sulfides were low. Among H 2SO 4, EDTA and NH 4HCO 3 extractant agents, H 2SO 4 was the most efficient and economic in removing the heavy metals, especially with the addition of the concentrated acid. Plant experiment in pots with Chinese cabbage ( Brassica Chinensis ) showed that the acidified sludges neutralized with alkaline amendments such as phosphate rock could increase significantly the plant yield and decreased the soil and plant contamination by heavy metals originated from sewage sludge.

Evaluating the Effects of Sustainable Chemical and Organic Fertilizers with Water Saving Practice on Corn Production and Soil Characteristics

The rapidly growing world population,water shortage,and food security are promising problems for sustainable agriculture.Farmers adopt higher irrigation and fertilizer applications to increase crop production resulting in environmental pollution.This study aimed to identify the long-term effects of intelligent water and fertilizers used in corn yield and soil nutrient status.A series of field experiments were conducted for six years with treatments as:farmer accustomed to fertilization used as control(CON),fertilizer decrement(KF),fertilizer decrement+watersaving irrigation(BMP1);combined application of organic and inorganic fertilizer+water-saving irrigation(BMP2),and combined application of controlled-release fertilizer(BMP3).A significant improvement was observed in soil organic matter(14.9%),nitrate nitrogen(106.7%),total phosphorus(23.9%),available phosphorus(26.2%),straw yield(44.8%),and grain yield(54.7%)with BMP2 treatment as compared to CON.The study concludes that integrating chemical and organic fertilizers with water-saving irrigation(BMP2)is a good approach to increasing corn productivity,ensuring water safety and improving soil health.The limitations of the current study include the identification of fertilizer type and its optimum dose,irrigation water type,and geographical position.

Effect of land-use changes on chemical and physical properties of soil in western Iran(Zagros oak forests)

The consequence of land-use change from forest to agriculture and other uses has become one of the world’s greatest concerns.The soil,one of the most important components of forests and containing all the required plant nutrients as soluble ions,is highly impacted by these changes.Because vast areas of the Zagros forests in western Iran have changed in use during the last few decades,the present study investigated the effects of landuse changes of forest area to agriculture,orchard,and agroforestry on soil chemical and physical properties.Soil was sampled at four land-use areas:less-disturbed forest areas(control)and agricultural,orchard,and agroforestry areas.Among each of the two forest-use areas(agroforestry and orchard),we selected five trees with similar-sized crowns and sampled under each tree crown at 0-15 and>15-30 cm depths.Five soil samples also were taken in agriculture area at each depth.The findings indicated that during land-use changes,soil sand particles decreased,and clay and silt particles of soil increased,resulting in a fine soil texture.Moreover,the amount of nitrogen(N),phosphorus(P),organic carbon(OC),and electrical conductivity(EC)of soil decreased at both depths due to the decrease in organic matter.Soil pH and magnesium(Mg)level rose during land-use change at both depths except at agricultural sites.Soil potassium(K)content decreased during agricultural use due to the elimination of tree cover.The level of K decreased only at the depth of 0-15 cm because of K dependency on parent materials.Generally,most soil nutrients were affected by plant removal in the conversion.Forest and agricultural soil are distinguishable by their properties,while land-uses such as agroforestry-orchard separated from the others.Soil nutrients were severely affected by the decrease and elimination of tree cover,plowing,and continuous harvesting,resulting in a decline in soil quality and fertility.

Assessment of Agricultural and Mining Pollutions of Waterbodies within the NakanbéBasin (Burkina Faso): The Case of the Goinré, Ziga and BagréReservoirs

Agriculture is harming its own future through soil degradation and pollution of the water that it generates. The different chemical analyses carried out on surface waters and the land surveys carried out in the Nakanbé basin have shown that agricultural practices contribute to water pollution. The monitoring of nitrate, orthophosphate and BOD5 levels in the dams of Goinré, Ziga and Bagré during the period from August to December revealed that agricultural practices lead to variation in these parameters. The average values for nitrates are 0.833 mg/L in the Goinré fresh waterbody, 1.372 mg/L in the Ziga reservoir, and 1.267 mg/L in the Bagré fresh waterbody. As for ortho phosphate, mean values are 0.357 mg/L in the Goinré reservoir, 0.157 mg/L in the Ziga reservoir and 0.123 mg/L in the Bagré reservoir. These average values are higher than the norms established by Nisbet and Vernaux (1970) for eutrophication. Nitrates and orthophosphate are the elements that contribute to the eutrophication of water surfaces in the Nakanbé basin, although this eutrophication is of low intensity. Of all pesticides encountered in our study sites, 45% are registered by the Sahelian Pesticides Committee (CSP): 35% are non-accredited and 20% are unknown in the global list authorized by the CSP in 2010.

Environmental Issues Related to Chemical Fertilizer Use in China

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Advances in Measures of Reducing Chemical Pesticides to Control Plant Diseases

In order to provide the technological support for further implementing measures of reducing chemical pesticide to control plant diseases,the research progress on non-chemical pesticide measures to control plant diseases are reviewed from the aspects of agricultural control,botanical pesticide control and microbial pesticide control,and the development prospects are proposed,including accelerating innovative research on botani-cal pesticide control such as Chinese herb extracts,and screening microbial pesticides from valuable bio-control bacteria or plant endophyte metabolites for commercial production and utilization.

农地流转的碳减排效应研究

农地流转可以促进农地的集中使用和规模化经营,会降低农业生产经营过程中的化学品和机械等生产性投入强度,并促进农作物种植结构“趋粮化”,进而降低农业碳排放强度。采用2011—2021年30个省份的数据检验农地流转率对农业碳排放强度的影响,结果表明:农地流转率提高对农业碳排放强度具有显著的负向影响;农地流转能够通过减少农业化学品和机械投入强度、提高粮食种植面积占比来降低农业碳排放强度。进一步分析发现,因流转对象和形式的不同,农地流转的碳减排效应存在异质性,表现为:相比流入农户、企业的农地流转,流入合作社的农地流转具有更为显著的碳减排效应;相比采用出租转包、互换转让形式的农地流转,采用股份合作形式的农地流转具有更为显著的碳减排效应。因此,应积极推动农地有序流转,不断完善农地流转机制,合理引导农地流转方向,并鼓励农地流转与农业碳减排项目相结合,以有效减少农业碳排放。

农业要素市场化对农业面源污染的影响效应——兼议环境规制的调节作用

本文探讨了农业市场化改革背景下,农业要素市场化对农业面源污染的影响效应、作用机制以及环境规制在其中的调节作用。基于2004—2020年中国省级(不含港澳台、西藏)面板数据,构建了动态面板模型,并运用差分广义矩阵及调节效应模型进行分析。研究结果表明:1)农业要素市场化对面源污染呈现倒“U”型的动态演化特征;2)机制分析表明,农业要素市场化通过种植结构效应、化学品投入效应和经营规模效应间接影响面源污染,具体而言,农业要素市场化对“非粮化率”和化肥投入强度存在倒“U”型影响,对人均经营规模的影响在市场化程度较高的后期显著为正;3)环境规制在“非粮化率”和化肥投入强度的传导机制中具有显著的负向调节作用,对经营规模与面源污染之间的传导关系不存在显著调节效应。因此,本文提出要进一步发挥市场化改革对农业污染治理的长效机制,立足农业面源污染治理“规模效应”“结构效应”和“投入品效应”的路径依赖,构建“政府-市场”双轨运行机制,以实现农业生态环境的改善和农业可持续发展。

中国农业减污降碳协同效应及其影响机制研究

农业面源污染与农业碳排放是中国农业面临的重要环境问题。现有研究忽视了农业面源污染治理与农业碳减排之间的协同关系,未探索农业减污降碳协同效应及其影响机制,影响农业可持续发展。为此,本文借鉴现有成果,提出农业减污降碳协同效应概念,基于2007—2021年中国30省份面板数据,利用双固定效应回归模型、调节效应模型对农业减污降碳协同效应及其影响机制进行实证分析,并讨论地区异质性。结果表明:1)农业减污降碳协同效应存在,农业面源污染与农业碳排放存在显著的协同关系,当农业面源污染减少时农业碳排放也将显著减少,该结果进行稳健性检验和处置内生性后依然成立;2)农业化学物资消费结构对农业减污降碳协同效应产生显著负向调节作用,农业化学物资使用效率与农业种植结构产生显著正向调节作用,农业投资规模产生负向调节作用但不显著;3)北方地区农业减污降碳协同效应比南方地区更为显著,农业化学物资消费结构与农业化学物资使用效率对北方地区农业减污降碳协同效应产生显著负向调节作用,农业种植结构对北方地区和南方地区农业减污降碳协同效应产生显著正向调节作用。因此,农业降污减碳协同效应存在。

新农科背景下植物化学保护课程“一优二转三创”改革研究与实践

对新农科背景下植物保护专业核心课程——植物化学保护开展“一优二转三创”教学改革的实例和成果进行了总结。通过优化课程内容、转变考核体系和评价机制、创新教学模式与手段,补齐了传统植物化学保护课程的授课短板。通过以上措施提高了学生的学习能力和实践能力,培养了学生“尚德崇学、稼穑厚生”的情怀,实现了价值引领、知识传授、能力培养的有机统一,为新农科背景下农科高等院校课程改革提供了借鉴。

羟基磷灰石与秸秆生物炭对青菜镉积累的钝化效应

农田重金属污染通过食物链危害人体健康,对土壤改良实现安全利用和保障农产品质量安全成为重要现实需求。本研究实地采集苏北Cd污染农田土壤分别进行模拟培养和温室蔬菜盆栽试验,探讨施加不同用量的羟基磷灰石(HAP,1%、2%)、水稻秸秆生物炭(BC,1%、2%)及其组合施用(0.5%HAP+0.5%BC、1%HAP+1%BC)对土壤Cd活性的钝化效率和降低青菜Cd吸收的效果并分析其作用机制。青菜盆栽试验表明,不同钝化剂处理均提高了叶片的净光合速率,生物量增加3.78%~124%,青菜Cd含量与土壤有效态Cd浓度分别降低16.1%~81.7%、15.8%~69.9%;40 d土壤培养试验后,各钝化剂对有效态Cd的降幅达28.9%~87.6%,主要机理是土壤pH显著提高了0.38~0.98个单位、Cd残渣态含量增加19.5%~37.0%、酸溶态含量减少21.1%~25.6%。可见,2种类型的钝化剂均主要通过降低土壤中Cd的化学活性和植物有效性来阻控其被蔬菜吸收积累,而在同等用量下的酸性污染土壤中,无机型材料HAP对提高蔬菜生物量和降低Cd吸收效果最佳且起效更快,其次则是HAP+BC复配的无机-有机复合型改良剂,但有机型材料BC则效果偏弱且起效慢,需要协同施用HAP提升钝化效率。

农业科研单位实验室安全管理探讨

农业科研单位实验室是开展科研工作的重要场所,承担着基础性、关键性科研任务的执行工作。实验室的安全使用和管理直接关系着科研人员的生命财产安全以及科学研究的顺利进行。文章分析了农业科研单位在实验室安全设施及危化品管控、实验室布局、人员安全意识等方面存在的问题,并从设置领导机构、建立并落实安全制度、科学合理布局实验室场地、增加安全设施投入、常态化开展安全警示教育活动等方面提出了加强科研单位实验室安全管理的建议及对策,以保障科研单位的科学实验工作能够顺利开展。

中国农业化学品使用效率测算及特征分析

综合利用三阶段DEA模型、超效率SBM模型和Malmquist指数模型,从静态特征和动态特征两个层面对2000—2019年中国30个省份的农业化学品使用效率及其变动趋势进行分析。研究发现:我国农业化学品使用效率具有较大的提升潜力,地区间农业化学品使用效率具有明显的时空特征差异;高效率地区数量先减后增,并由传统作物主产地区向华南地区扩展;西北地区和京津地区属于低效率地区,高效率地区主要分布在平原地带。从动态特征来看,我国农业化学品使用效率整体稳中有升,受技术进步影响呈现阶段性变化。我国应持续挖掘农业化学品减量增效潜力,加强新型农业化学品减量与替代技术的研发与推广,优化农业生产资源配置和区域布局。

壳聚糖及其纳米粒在农业领域的应用研究进展

壳聚糖是一种从几丁质生产的天然、安全且低成本的生物聚合物,因其独特的性质,在工业生产中具有广泛的应用前景。本综述聚焦于壳聚糖及其纳米粒在农业领域的多重作用,特别是在种子处理、土壤修复、肥料和农药增效方面。研究表明,壳聚糖可用于种子包衣,形成物理屏障以抵御病原体侵染,并且其抗菌活性有助于促进作物生长及提高对非生物和生物胁迫的耐受性。此外,低分子量壳聚糖能显著诱导植物的抗病性。近年来,壳聚糖纳米粒作为一种新型载体,已被开发用于包裹杀虫剂、杀菌剂、肥料和微量元素等,旨在实现农药和肥料使用的减量化和效率化,进而推动农业的可持续发展。最后,本研究还探讨了壳聚糖及其纳米粒的未来研究方向。

农业面源污染多元主体协同治理策略的演化分析

有机肥替代化肥是降低氮磷污染概率,减轻农业面源污染的有效途径。当前,政府正全力应对的生态污染问题,但利益相关者间的利益冲突使政策难以发挥预期效力。为此,从肥料的生产和流通环节着手,构建包含政府、农用肥料生产企业、农户的演化博弈模型,从市场供需角度探究初始意愿、奖惩制度、成本和收益等因素对有机肥替代政策执行效率的影响,进而探索农业面源污染多元主体协同治理路径。结果表明:共有3组演化稳定的策略组合,分别为(宽松监管,不生产商品有机肥,不替代化肥)、(宽松监管,生产商品有机肥,替代化肥)和(严格监管,不生产商品有机肥,不替代化肥)。有机肥替代行为的获利能力是使结果稳定于(宽松监管,生产商品有机肥,替代化肥)的关键。肥料市场的供需平衡是博弈均衡的实质,其中,企业的初始意愿对结果更具导向性。三方主体的决策过程具备利益导向特征,在财政支持范围内加大奖惩力度可提高企业与农户生产、施用商品有机肥的意愿。据此,建议政府以经济效益为宣传导向,通过强化环保宣传教育、合理制定经济政策、搭建技术合作平台等污染治理路径,构建起协同治理的长效机制。

基于熵值法的四川省农业可持续发展研究

四川省作为我国人口大省、农业大省,提高四川省农业可持续发展水平成为农业研究人员关注的问题。四川省2004—2020年数据熵值法分析表明,2004—2010年,四川省农业可持续发展综合评分逐年下降,2010年达到最低0.035;2010—2020年,四川省农业可持续发展水平处于不断上升态势,并且上升幅度逐年增大。熵权法赋值计算后发现,化肥施用量、农用塑料薄膜使用量对四川省农业可持续发展水平的影响相对较大,减少其可以促进农业可持续发展。

高效环保型化肥生产工艺的研究与应用

随着农业生产的持续发展,化肥作为提高作物产量的重要手段,其需求日益增大。然而,传统化肥生产工艺往往伴随着能耗高、污染重等问题。因此,研究高效环保型化肥生产工艺对于实现农业可持续发展具有重要意义。综述了高效环保型化肥生产工艺的研究现状,探讨了新型工艺的技术特点及其在农业生产中的应用效果,旨在为化肥产业的绿色发展提供参考。