越冬期地面灌溉技术研究

基于越冬期大田土壤入渗和灌水试验,采用试验研究和模拟分析相结合的方法,分析讨论了冬灌水流运动特点,揭示了表征灌溉效果的各项指标随地中温度的变化特性,提出了提高越冬期灌溉灌水效果的5项技术:短畦灌溉技术、长畦灌溉技术、小流量灌溉技术、秋耕灌溉技术和最冷月免灌技术。研究结果对我国北方缺水地区冬季合理灌溉具有重要指导意义。     

贵州无公害番茄栽培专家系统的开发研究

贵州无公害番茄栽培专家系统是基于PAID 4.0开发平台研制的。系统将人工智能与番茄栽培领域专家的知识结合起来,模拟农业专家指导农户进行无公害番茄栽培,具有技术先进、功能丰富、结构规范、界面友好、易学实用等特点,可有效地解决目前贵州无公害番茄生产中专家型农业科技人员的短缺问题,为农业科技咨询服务提供新途径。     

食品中农药残留分析方法的研究进展

由于农药残留引发的食品中毒事件时有发生,食品安全已受到人们的广泛关注和重视。因此,加强对农药残留分析方法的研究和加大对农药残留的检测力度非常重要。对近年来食品中农药残留分析的样品处理和检测方法进行了较为全面的概述,提出了农药残留分析的发展趋势。     

Remediation of amide pesticide-polluted soils by combined solarization and ozonation treatment

Agriculture has a close relationship with nature, but it can also be the source of negative and permanent environmental effects. The use of pesticides in modern agriculture is a common practice, but their side effects on the environment cannot be disregarded. In this study, we evaluated a combination of solarization and ozonation techniques for the elimination of six amide pesticides (boscalid, chlorantraniliprole, cyflufenamid, fluopyram, napropamide, and propyzamide) in soil. Initial experiments were performed with four different soils to assess the efficiency of this methodology at different soil temperatures and ozone dosages under laboratory conditions, and then a greenhouse pot experiment was conducted under controlled conditions during summer. Fifty days after the onset of the experiments, higher degradation percentages of amide pesticides were observed in ozonized soils than in other treated soils, particularly when ozone was applied at 10 cm soil depth. The results show that the utilization of ozonation, along with solarization, represents a valid method for degrading residues of the studied pesticides and suggest that this combined technology may be a promising tool for remediating pesticide-polluted soils.     

分析技术在土壤微塑料研究中的应用现状

微塑料污染已成为环境领域研究的热点问题。受采样、前处理和分析技术的限制,现有研究中检测到的微塑料尺寸普遍较大。定量分析技术不够成熟,文献数据之间的可比性较差。复杂组分和表面附着物导致土壤微塑料的分析检测存在更大的挑战。为更好地掌握研究现状与发展趋势,本文从光谱分析、热分析、显微分析等角度分类,对土壤微塑料研究中的分析技术进行了解析、对比和总结。光谱分析对微塑料进行定性和数量统计,常见的有傅里叶变换红外光谱法和拉曼光谱法。热分析用于组分鉴定和质量分析,具体分为裂解气质联用和热重波谱联用。显微分析则对形貌和尺寸进行表征,包括光学显微镜和电子显微镜两种。提出微塑料分析技术越来越丰富,但是针对土壤微塑料的分析是一项复杂的工作。分析技术的标准化是评价和治理微塑料污染的关键;现有的土壤微塑料检测方法各有利弊。组合或联用技术的使用有望更高效、精准地实现对土壤微塑料定性定量分析;应从需要解决的科学问题出发,根据研究目的合理选择分析技术;部分分析技术在土壤微塑料的实际测定有待于进一步的探索与验证。     

含水量和容重对旱地耕层土壤热导率的影响及预测

土壤热导率是研究地表能量平衡和土壤水热运移过程中的一个基础参数。受土壤耕作、干湿交替和根系生长等过程的影响,耕层土壤的含水率和结构呈现较强的变异特征,而目前缺乏关于定量分析耕层土壤热导率变异特征的研究。该研究利用田间定位试验,采用热脉冲技术测定了含水率和容重变化条件下耕层土壤热导率的变异特征,并利用传递函数模型对耕层土壤热导率进行了预测。结果表明:含水率和容重是影响耕层土壤热导率变异的主要因子,而耕作强度和干湿交替是这种变异的关键驱动力;与翻耕和旋耕处理相比,免耕处理提高了土壤容重和含水率,从而增大了土壤热导率;在干湿交替作用下,翻耕后土壤容重逐步增加,耕层热导率也呈现上升趋势,波动幅度与含水率的变化相关。基于含水率、容重和质地信息,土壤热导率传递函数模型可以给出可靠的田间土壤热导率估计值,其均方根误差和平均偏差分别为0.09和-0.01 W/(m·K);考虑耕层土壤容重的动态信息,可以提高该模型预测土壤热导率的准确性。     

Involvement of Bradyrhizobium japonicum denitrification in symbiotic nitrogen fixation by soybean plants subjected to flooding

Denitrification by Bradyrhizobium japonicum bacteroids contributes to nitric oxide (NO) production within soybean nodules in response to flooding conditions. However, the physiological relevance of NO production by denitrification in B. japonicum-Glycine max symbiosis is still unclear. In this work, soybean plants were inoculated with B. japonicum strains lacking the nirK or norC genes which encode the copper-containing nitrite reductase and the c-type nitric oxide reductase enzymes, respectively. 14 days flooding increased nodule number of plants inoculated with the WT and norC strains, but not of plants inoculated with the nirK mutant. However, nodule dry weight was not affected by 14 days flooding regardless of the strain used for inoculation. Supporting this observation, individual nodule growth was significantly higher in plants inoculated with nirK than those inoculated with WT or norC after 14 days flooding. Nodule functioning was strongly inhibited by flooding since leghemoglobin content of the nodules induced by any of the strains was significantly decreased after 7 or 14 days flooding compared to control plants. However, this effect was more relevant in nodules of plants inoculated with the WT or norC mutant than in those inoculated with the nirK mutant. Nitrogen fixation was also estimated by analyzing nitrogen content derived from biological nitrogen fixation in shoots, using the ¹⁵N isotope dilution technique. By using this approach, we observed that the negative effect of 14 days flooding on nitrogen fixation was more pronounced in plants inoculated with the norC mutant. However, nitrogen fixation of plants inoculated with nirK showed the highest tolerance to 14 days flooding. These findings allowed us to demonstrate the previously proposed hypothesis which suggests that NO formed by copper-containing nitrite reductase in soybean nodules, in response to flooding, has a negative effect on nitrogenase activity. We propose that inoculation of soybeans with a B. japonicum nirK mutant, which does not produce NO from nitrate, increases the tolerance of symbiotic nitrogen fixation to flooding.     

横垄耕作的面源污染截留效应研究

为了解横垄耕作的面源污染截留效应,选取吉林省长春市莫家沟小流域横垄耕作坡耕地为研究区,应用210Pbex核素示踪技术得到研究区土壤侵蚀模数为2 268 t/(km2.a),吸附态氮、磷流失负荷分别为4 889、2 022 kg/a;运用RU-SLE2.0模型,模拟在同等立地条件下顺坡耕作土壤侵蚀模数约为6 200 t/(km2.a)。对比结果表明:横垄耕作较顺坡耕作可减少约63%的土壤流失量及随土壤流失的吸附态氮磷负荷。     

水稻穴播同步侧位深施肥技术试验研究

根据水稻种植的农艺要求,在同步开沟起垄水稻精量穴播技术的基础上进一步提出了一种水稻穴播同步侧位深施肥技术。调查了在不同种植方式条件下不同品种的水稻根系在稻田中的分布情况,根据根系的分布情况研究了深施肥技术参数,确定了深施肥深度以不超过10 cm为宜,研究了培杂泰丰、玉香油占2种品种水稻施入0~5 cm土层与5~10 cm土层中的肥料比例关系。试验结果表明华南农业大学研制的同步开沟起垄侧位深施肥水稻精量穴播机能满足水稻穴播同步侧位深施肥技术的要求,可以作为实施水稻穴播同步侧位深施肥技术的载体。生产试验表明:水稻穴播同步侧位深施肥技术具有增产、节本的效用。在同等的施肥条件下,机械播种及深施肥处理的有效穗、穗平均实粒数、结实率均高于机械播种人工撒施肥和人工撒直播人工撒施肥,增产418.5~957 kg/hm2,增幅5.86%~13.41%。该文研究可为深施肥机具的设计提供参考依据。     

Impacts of soil erosion on organic carbon and nutrient dynamics in an alpine grassland soil

The impact of soil erosion on the nutrient dynamics in alpine grassland soils is still an essential problem. Selecting a grass-covered hillslope in eastern Tibet Plateau, the cesium-137 (¹³⁷Cs) technique was used to determine the impacts of soil erosion on soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), and total potassium (TK). The ¹³⁷Cs data revealed that there were distinct soil redistribution patterns in different hillslope positions because of the influences of slope runoff, plant coverage and grazing activity. For the upper slope, soil erosion first decreased downward, followed by soil deposition in its lower part. In contrast, for middle and toe slopes, there was an increasing soil erosion along a downslope transect. Across the lower slope, soil erosion showed an irregular variation. Influenced by the selective transport of water erosion, SOC, TN and TP storage decreased with increasing soil erosion in upper, middle and toe slopes. In contrast, SOC, TN and TP storage varied little with soil erosion in the lower slope. On the whole hillslope, TK storage also varied little with soil erosion due to the large amount of potassium elements derived from soil parent materials. Particularly noteworthy was the greatest storage of SOC, TN and TP in the lower slope where most obvious net soil erosion occurred, which is closely related to the humus accumulation combined with gravel separation as well as weathering and pedogenesis of parent rocks induced by soil freeze-thaw.