耕作方式对耕层土壤结构性能及有机碳含量的影响

为了寻求能够提高土壤结构稳定性的耕作模式,在陇中黄土高原半干旱区连续7年的定位试验研究基础上,采用常规分析方法(湿筛法、重铬酸钾容量法、环刀法),研究了不同耕作方式对耕层土壤结构性能及有机碳含量的影响.结果表明:与传统耕作(T)相比,免耕无覆盖(NT)、传统耕作+秸秆还田(TS)和免耕+秸秆覆盖(NTS)3种保护性耕作方式均能不同程度地增加耕层土壤的有机碳和不同粒径水稳性团聚体的含量,其中免耕+秸秆覆盖(NTS)处理效果最佳.在0～10 cm土层中,NTS处理的土壤容重低、孔隙度大,土壤结构得到了较大改善.不同耕作方式下0～5 cm、5～10 cm和10～30 cm土层粒径1～0.5 mm水稳性团聚体的含量最高,粒径>0.25 mm水稳性团聚体含量与有机碳含量和孔隙度呈显著正相关,与容重呈显著负相关.     

新疆绿洲农田不同开垦年限土壤有机碳及不同粒径土壤颗粒有机碳变化

研究不同开垦年限新疆绿洲农田土壤有机碳及不同粒径土壤颗粒有机碳的变化规律,评价长期垦殖对新疆绿洲农田土壤有机碳的影响。以相应未开垦地为对照,选取南北疆兰州湾、31团和普惠农场三个典型绿洲不同开垦年限土壤为研究对象,应用物理分组方法研究不同粒径土壤颗粒中有机碳含量及分布。结果表明:(1)开垦有利于新疆绿洲农田土壤总有机碳的积累,开垦初期(0～5a)增加迅速,年均增加0·5gkg-1,10a后增加趋于平缓。(2)垦殖增加了不同粒径土壤颗粒有机碳的含量,砂粒有机碳在垦殖10a间达到最大值后趋于相对稳定的水平;粉砂粒和黏粒有机碳随垦殖年限延长增加。(3)开垦提高了POC/MOC值,表现为开垦初期(0～5a)增加迅速,10a左右达到最大值后开始下降。研究说明,新疆绿洲区域未开垦地开垦增加了土壤总有机碳和不同粒径土壤颗粒有机碳含量,随垦殖年限延长,粉砂粒和黏粒有机碳成为绿洲农田土壤主要碳库,土壤自身生产力存在下降可能,土壤质量存在潜在退化风险。     

Plant‐based fertilizers for organic vegetable production

To ensure high yield and quality in organic vegetable production, crops often require additional fertilizer applied during the season. Due to the risk of contamination of edible plant products from slurry, plant‐based fertilizers may be used as an alternative. The purpose of our work was to develop mobile green manures with specific high nutrient concentrations (e.g., nitrogen [N], sulfur [S], and phosphorus [P]) that are released quickly after soil incorporation and that are easy to handle during storage and application. To distinguish from traditional green manures that are grown to improve soil fertility, the term “mobile green manures” is used for green‐manure crops that are harvested in one field and then moved as a whole and used as fertilizer in other fields. To further investigate mobile‐green‐manure crops for use as efficient fertilizers, pot and field experiments were conducted with cauliflower (Brassica oleracea botrytis) and kale (Brassica oleracea sabellica) supplied with organic matter consisting of a wide range of plant species with varying nutrient concentrations. Further, field experiments were conducted with leek (Allium porrum) and celery (Apium graveolens dulce) supplied with increasing amounts of organic matter consisting of fresh, ensiled, or dried green manures. Results show that garden sorrel (Rumex acetosa), dyer's woad (Isatis tinctoria), and fodder radish (Raphanus sativus) harvested with a high leaf‐to‐stem ratio resulted in high P concentration, and cruciferous crops in high S concentration. Dyer's woad, salad burnet (Sanguisorba minor), and stinging nettle (Urtica dioica) showed high boron (B) concentration, whereas species such as dandelion (Taraxacum officinale), chicory (Cichorium intybus), and garden sorrel showed high potassium (K) concentration. Green manures with high P and S concentrations increased the nutrient uptake and yield of pot‐grown cauliflower and kale. Field experiments showed that the production of cauliflower and kale decreased when the carbon‐to‐nitrogen (C : N) ratio of applied green manure increased. In kale, for example, application of 160 kg N ha^–1 in early harvested lucerne (Medicago sativa) with a C : N ratio of 10 resulted in the highest kale production whereas application of an equal amount of N in late harvested lucerne with a C : N ratio of 20 produced 34% less. Differences in vegetable production were not due to the amount of N applied, but to the N availability. Field experiments with fresh, ensiled, or dry green manure applied to leek and celery showed that the C : N ratio has to be low to get a fast response. Further, these field experiments demonstrate the importance of green manures, which can be stored and are easy to handle during transport, crop application, and soil incorporation. It is concluded that it is possible to produce green manures with high concentrations of S, P, K, and B, and low C : N ratios and that these properties have a great impact on the value of the green manure for vegetable production.     

有机无机氮肥配施对典型菜地土壤微生物和酶活性的影响

为了比较不同种类有机无机氮(N)肥配施后典型菜地土壤微生物和酶活性的差异,揭示施用有机物料后微生物在调节土壤肥力中的作用,以猪粪、沼渣沼液和猪粪堆肥为供试材料,采用田间小区试验,设置不施肥(CK)、不施N肥(PK)、纯施化肥(NPK)、有机无机肥配施1(20%猪粪N+80%化肥N,NPKM1)、有机无机肥配施2(20%沼渣沼液N+80%化肥N,NPKM2)和有机无机肥配施3(20%猪粪堆肥N+80%化肥N,NPKM3)等6种施肥模式,连续3年(2011-2013年)研究不同有机无机N肥配施对典型菜地土壤微生物和酶活性的影响。结果表明:小白菜季和莴苣季生育期间土壤细菌数量呈上升趋势,土壤真菌、放线菌数量呈先升后降趋势,且栽培后季较前季高。与NPK处理相比,NPKM1、NPKM2、NPKM3处理土壤细菌数量提高2.27%~26.16%(小白菜季),15.06%~40.82%(莴苣季);真菌数量提高33.62%~47.10%(小白菜季),39.64%~52.27%(莴苣季);放线菌数量提高6.59%~38.21%(小白菜季),20.97%~29.66%(莴苣季)。有机无机N肥配施可以促进菜地土壤微生物大量繁殖。与NPK处理相比,NPKM1、NPKM2、NPKM3处理提高土壤脲酶、磷酸酶、过氧化氢酶、纤维素酶的活性。有机无机N肥配施可以促进菜地土壤酶活性的提高。各处理蔬菜产量分别为6.73~22.50 t/hm2(小白菜),21.54~47.79 t/hm2(莴苣),大小均表现为NPKM3NPKM1NPKM2NPKPKCK。相关分析表明,小白菜和莴苣产量与土壤微生物数量和酶活性之间均存在密切关系。总之,有机无机N肥配施可以有效提高土壤中微生物数量和酶活性,维持菜地较高的土壤肥力,有利于蔬菜种植的可持续和高效生产,以猪粪堆肥配施效果最佳。     

有机肥对旱地莜麦生长发育的影响

经过3年的研究表明,合理施用有机肥料,不仅能提高旱地莜麦产量,获得高产和稳产,而且能有效地提高土壤肥力,增加土壤养分。只增施化肥,不施或少施有机肥,不仅莜麦产量较低,而且导致土壤养分逐渐减少,土壤有机质逐年下降,土壤板结。     

土壤有机质含量对化肥氮素转化的影响

采用室内好气培养,分期采样,室内分析的研究方法,研究了土壤有机质含量对化肥氮素形态转化的影响。结果表明,化肥施入土壤后,土壤铵态氮供出量在培养前期(20d)随有机质含量的增加而增加,在培养中后期则并未表现出这种趋势;在不同培养阶段土壤硝态氮供出量与土壤有机质含量相关系数在0.8325￣0.9953之间,呈显著正相关;土壤无机氮供出量在培养至第7天、第20天时,与土壤有机质含量相关系数分别为0.973、0.9854,其相关性达到了极显著,不过在培养的中后期,二者的相关性并不明显。     

华北平原小麦施肥现状及影响小麦产量的因素分析

针对近年来华北平原水肥投入不断增加而小麦单产徘徊不前的局面,本研究对山东省惠民县小麦的施肥现状和影响小麦产量的主要因素进行了调查。结果表明,研究地区小麦季农民习惯的氮磷钾肥投入量在不同农户间差异较大,平均为424 kg/hm2N,226 kg/hm2P2O5,88 kg/hm2K2O,其中氮磷肥用量已远超过同期作物养分消耗量。在现有的小麦产量水平和施肥水平条件下,土壤有机质含量和亩穗数对小麦产量的贡献最大,其次为土壤速效磷含量和穗粒数,土壤速效钾和千粒重与小麦籽粒产量没有明显相关性。由于过量氮磷肥施用和高的土壤速效钾含量,不同农户间施肥量的差异对小麦产量影响较小。     

柴油机全工况下抽气回热式有机朗肯循环系统分析

针对一台车用柴油机的排气能量变化规律,建立了抽气回热式有机朗肯循环(RORC)系统,分别采用纯工质R245fa和非共沸混合工质Mix(异戊烷与R245fa按照摩尔比例7∶3组成的混合工质),研究了抽气压力这一参数对RORC系统净输出功率、系统热效率、工质质量流量等性能的影响;进而确定Mix抽气压力1.15 MPa,R245fa抽气压力1.2 MPa,在柴油机全工况范围内,对比分析了采用2种工质的RORC系统的净输出功率、效率、工质质量流量等性能随柴油机转速和转矩的变化情况,结果显示,在柴油机全工况范围内,与采用R245fa的RORC系统相比,采用Mix作为工质的RORC系统的余热回收效果更佳。     

有机栽培基质在矮牵牛育苗及栽培中的应用研究

以河南农业大学研制的基质为原料,成熟的草炭配方为对照,梦幻系列矮牵牛为供试品种,通过与不同辅料配比,对不同的有机发酵基质进行筛选。结果表明:在所用基质中,B基质的综合性状优于其他基质,特别是以B基质为主的处理T8,可以代替草炭的成熟基质配比。B基质的发酵配方比为:玉米秸秆粉碎料100kg+花生壳粉碎料65kg+烘干鸡粪20kg+中温发酵菌0.3%+水220kg;处理T8的配比为,B基质∶过磷酸钙∶蛭石=21∶1∶2。     

农业院校中开展绿色化学教学的构思探讨

阐述了在农业院校中开展绿色化学教学的重要意义,提出了在有机化学教学中开展绿色化学实践的设想与措施。