Light fraction organic N, ammonium, nitrate and total N in a thin Black Chernozemic soil under bromegrass after 27 annual applications of different N rates

Anadequate supply of N for a crop depends among others on the amounts of N thataremineralized from the soil organic matter plus the supply of ammonium andnitrateN already present in the soil. The objective of this study was to determine thebehaviour of light fraction organic N (LFN), NH₄-N, NO₃-Nand total N (TN) in soil in response to different rates of fertilizer Napplication. The 0–5, 5–10, 10–15 and 15–30cm layers of a thin Black Chernozemic soil under bromegrass(Bromus inermis Leyss) at Crossfield, Alberta, Canada,weresampled after 27 annual applications of ammonium nitrate at rates of 0, 56,112,168, 224 and 336 kg N ha^–1. The concentration andmass of TN and LFN in the soil, and the proportion of LFN mass within the TNmass usually increased with N rates up to 224 kg Nha^–1. The increase in TN mass and LFN mass per unit ofNadded was generally maximum at 56 kg N ha^–1 anddeclined with further increases in the rate of N application. The percentchangein response to N application was much greater for the LFN mass than for the TNmass for all the N rates and all soil depths that were sampled. Mineral N intheform of NH₄-N and NO₃-N did not accumulate in the soil at 112 kg N ha^–1 rates, whereas theiraccumulation increased markedly with rates of 168 kg Nha^–1. In conclusion, long-term annual fertilization at 112 kg N ha^–1 to bromegrass resulted insubstantial increase in the TN and LFN in soil, with no accumulation ofNH₄-N and NO₃-N down the depth. The implication of thesefindings is that grasslands for hay can be managed by appropriate Nfertilization rates to increase the level of organic N in soil.     

Total and light fraction organic C in a thin Black Chernozemic grassland soil as affected by 27 annual applications of six rates of fertilizer N

Maintenance and sequestration of C is important to sustain and improve the quality and productivity of soils. The objective of this study was to determine the effects of 27 annual applications of six N rates (0, 56, 112, 168, 224 and 336 kg N ha^–1 yr^–1) on total organic C (TOC) and light fraction organic C (LFOC) in a thin Black Chernozemic loam soil. Nitrogen (ammonium nitrate) was surface-applied to bromegrass (Bromus inermis Leyss) managed as hay near Crossfield, Alberta, Canada. The concentration and mass of TOC and LFOC in the 0–5, 5–10, 10–15 and 15–30 cm soil layers increased with N rate and showed a quadratic response to N rate with significant R² values, with their maximum values at 336 kg N ha^–1 in the 0–5 cm layer and at 224 kg N ha^–1 in other layers. But the increase in TOC and LFOC per kg of N addition was maximized at 56 kg N ha^–1 and declined with further increase in N rate. These trends indicated that higher N rates would cause a faster build up of soil C, whereas lower N rates would achieve a greater increase in soil C per unit of N addition. Response of C mass to N application was much greater for LFOC (range of 697 to 156% increase) than for TOC (range of 67 to 17% increase). Percentage of LFOC in TOC mass increased with N rate. At the 168 to 336 kg N ha^–1 rates, almost all of the increase in TOC in the surface 10 cm soil occurred as LFOC. Thus, LFOC was more responsive to N application and was a good indicator of N effect on soil C. The trend of change in soil TOC and LFOC was similar to hay yield and C removal in hay, which suggests that increasing hay yield with N application concurrently also increases soil organic C. In conclusion, long-term annual applications of N fertilizer to bromegrass resulted in a substantial increase in TOC and LFOC in the soil, thereby indicating that N fertilization can be used to sequester more atmospheric C in prairie grassland soils.     

平衡施肥应重视中、微量元素的有效施用

叙述平衡施肥对农作物生长的重要意义,分析平衡施肥与农作物平衡吸收的矛盾,提出跨越农作物平衡吸收的措施。并提出平衡施肥也应重视中微量元素的施用,才能有效提高农作物的产量和质量,提高肥料的利用率,减少化肥对环境的污染,提高农民的产出与投入比。     

试论现代化肥施用技术

根据普遍使用较大数量化肥是我国现代农业发展的重要标志,指出应用现代施肥技术是提高肥效、减少化肥对生态环境等负面影响的基本途径。提出现代施肥技术的核心和关键在于把化肥施到作物吸收根系的分布区域。阐述现代施肥技术基本原则:把任何化肥都施到作物根系的伸展区域,供作物快速有效吸收;将化肥溶于水制成营养液后随水灌施,能明显提高水、肥的利用率。     

预测半悬挂犁与二轮驱动轮式拖拉机组动态侧向性能的计算机模型

本文根据离散系统动力学原理建立了半悬挂犁—拖拉机系统模型,该模型考虑了发动机扭矩、差速器、左右轮胎不同增重、犁体和轮胎侧向力以及半悬挂犁挂结参数和设计参数等因素,测量值与用该模型预测值基本一致。该模型可用于预测半悬挂犁与二轮驱动轮式拖拉机的动态侧向性能,并能优化该系统。     

新强煤矿自制刨煤机在薄煤层中的应用管理

七台河矿业精煤集团公司新强煤矿研制的刨煤机在薄煤层开采中发挥了重要的作用,取得了显著效果,走出了一条新路子。文章重点介绍了自制刨煤机的基本原理和使用情况。     

轻简高效栽培技术研究现状

随着农业的可持续发展和"一带一路"发展战略的持续推进,我国农业产业结构将由"生产型农业"向"服务型农业"转变。由于我国农业人工和农资的高投入低效益、农田土地资源利用率低以及闲置等问题一直存在,因此,以节本增效、绿色低碳、创新驱动、集约智能为核心技术,以服务为导向的轻简高效栽培模式,将成为我国农业发展的必然趋势。本文从轻简施肥、覆盖栽培、机械化、农田土地规划利用等我国农业目前存在的主要问题论述了近年来国内轻简栽培技术所取得的主要成果,以及存在的一些问题和发展方向。     

特殊条件下GH9自动刨煤机采煤工艺探讨

介绍了工作面伪倾角达到9°～10°、头尾落差超过32m时,GH9全自动刨煤机所采取的特殊工艺。     

长期施肥对旱地土壤有机磷及其组分的影响

通过15年长期定位试验,采用Bowman和Cole提出的土壤有机磷分级方法,研究了不同耕作施肥措施对旱地耕层土壤有机磷及其组分的影响。结果显示旱地土壤各个处理的活性有机磷含量低,占有机磷总量的比例低于3.6%,中活性有机磷为有机磷的主体,约占有机磷总量的73.37%-91.54%。休闲、撂荒及磷肥与其它肥料配合使用,均增加了耕层土壤的中活性有机磷含量,增加了中稳性有机磷含量及其比重;休闲、撂荒及磷钾提高了高稳性有机磷含量及比重,而氮磷钾及其与有机肥配合处理则降低了高稳性有机磷的含量。尽管不同耕作施肥管理均影响旱地土壤有机磷含量,但是施用有机肥对有机磷的增加贡献最大;撂荒与休闲相比,前者更有利于土壤有机磷的积累。     

平衡施肥是复混肥料配方和生产的依据

阐述农作物所需养分在作物中的分布和在土壤中的去向。说明现代施肥技术的重要性,这将带来巨大的经济效益、社会效益和环境效益。列举平衡施肥试验、示范、推广的事例,说明其科学性。确定的养分配方和使用量,使作物增加产量,提高质量,并减少对环境的负面影响。在市场经济下,化肥企业要供应对路产品,平衡施肥是确定复混肥料配方和生产的依据。