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41.
农业职业教育是服务"三农"的教育。针对农村剩余劳动力提出农民学分制学历教育培养模式,将课堂搬到"田间地头",最大限度地发挥农业职业学校服务于经济社会的职能,结合教育与生产实际,融合专业与产业,实现让广大农民接受教育的目标。 相似文献
42.
Xiaosha Li Huifang Han Tangyuan Ning Ying Shen Rattal Lal 《Soil Use and Management》2019,35(4):585-594
To assess changes in organic carbon pools, an incubation experiment was conducted under different temperatures and field moisture capacity (FMC) on a brown loam soil from three tillage practices used for 12 years: no‐till (NT), subsoiling (ST) and conventional tillage (CT). Total microbial respiration was measured for incubated soil with and without the input of straw. Results indicated that soil organic carbon (SOC) and microbial biomass carbon (MBC) under ST, NT and CT was higher in soil with straw input than that without, while the microbial quotient (MQ or MBC: SOC) and metabolic quotient (qCO2) content under CT followed the opposite trend. Lower temperature, lower moisture and with straw input contributed to the increases in SOC concentration, especially under NT and ST systems. The SOC concentrations under ST, with temperatures of 30 and 35°C after incubation at 55% FMC, were greater than those under CT by 28.4% and 30.6%, respectively. The increase in MBC was highest at 35°C for 55%, 65% and 75% FMC; in soil under ST, MBC was greater than that under CT by 199.3%, 50.7% and 23.8%, respectively. At 30°C, the lower qCO2 was obtained in soil incubated under NT and ST. The highest MQ among three tillage practices was measured under ST at 55% FMC, NT at 65% FMC and CT at 75% FMC with straw input. These data indicate the benefits of enhancing the MQ; the low FMC was beneficial to ST treatment. Under higher temperature and drought stress conditions, the adaptive capacity of ST and NT is better than that of CT. 相似文献
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通过设置黑豆-油菜、大豆-油菜的轮作模式在湖南醴陵进行大田试验,结果发现黑豆表现出较强的镉富集能力,其根、茎、叶及果壳中镉含量分别为2.14、2.63、4.10及1.34 mg/kg,富集系数均在1以上。油菜各个部位镉含量较高的分别为叶与茎,达到了7.13和4.73 mg/kg。黑豆各部位镉转运系数均高于大豆,各油料作物提取的重金属主要集中在茎与叶。大豆叶的镉富集系数为2.06,茎的镉富集系数为0.86,明显低于黑豆同部位的富集能力。每公顷土地经过一轮黑豆-油菜、大豆-油菜轮作分别能够从土壤中提取73.52 g和51.68 g的镉,对土壤重金属镉的修复效率约为3%。 相似文献
45.
不同施肥方式对红壤蔬菜田氨氧化细菌和氨氧化古菌群落的影响 总被引:1,自引:0,他引:1
通过构建氨单加氧酶基因(amoA)克隆文库,研究在红壤蔬菜田上只施用磷钾化肥(PK)、只施氮磷钾化肥(NPK)、施用腐熟有机肥(DNPK)和施用新鲜有机肥(FNPK)等4种不同施肥处理的土壤氨氧化细菌(AOB)和氨氧化古菌(AOA)群落多样性及与土壤脲酶活性的相关性。结果表明:施加有机肥处理(DNPK和FNPK)的蔬菜田土壤的AOB文库和AOA文库OTU数量和Shannon指数高于只施用无机肥(NPK和PK)处理的蔬菜田土壤;DNPK和FNPK处理的土壤优势AOB菌群为多形亚硝化叶菌(Nitrosolobus multiformis),比例分别为88.5%和68.5%,NPK和PK处理的土壤优势AOB菌群为亚硝化单胞菌属(Nitrosospirasp.),比例分别为54.8%和65.5%;DNPK、FNPK、NPK和PK处理土壤优势AOA菌群均为阿伯丁土壤亚硝化细杆菌侯选种(CandidatusNitrosotalea devanaterra),比例分别为90.9%、84.4%、77.8%和45.2%;施加有机肥处理(DNPK和FNPK)的土壤脲酶活性和氨氧化微生物的多样性指数都高于只施用无机肥处理(NPK和PK);AOA群落多样性指数与土壤脲酶活性呈显著正相关,而AOB群落多样性与土壤脲酶活性相关性不显著。总体来看,有机肥比无机肥处理提高了AOA和AOB群落多样性,且AOA在红壤蔬菜田土壤氨氧化过程中起着更为重要的作用。 相似文献
46.
Crop rotation and tillage systems have important implications for weed infestation and crop productivity. In this study, five tillage systems viz. zero tillage (ZT), conventional tillage (CT), deep tillage (DT), bed sowing (60/30 cm with four rows; BS1) and bed sowing (90/45 cm with six rows; BS2) were evaluated in five different crop rotations viz. fallow-wheat (FW), rice-wheat (RW), cotton-wheat (CW), mungbean-wheat (MW) and sorghum-wheat (SW) for their effect on weed infestation and productivity of bread wheat. Interaction between different tillage practices and cropping systems had significant effect on density and dry biomass of total, broadleaved and grass weeds, agronomic and yield-related traits, and grain yield of bread wheat. The un-disturbed soils (ZT) under fallow-wheat or mungbean-wheat rotations favoured the weed prevalence (a total weed dry biomass of 72.4–109.6 and 105.6–112.1 g m−2 in first and second year, respectively). Contrary to this, the disturbed soils (CT, DT, BS1 and BS2) had less weed infestation with either of the rotations (a total weed biomass of 0.4–7.1 and 1.1–5.4 g m−2 in first and second year, respectively). Sorghum-wheat rotation had strong suppressive effect on weed infestation in all tillage systems. The impact of crop rotation was more visible during second year of experimentation. Bed sown wheat (BS1 and BS2) in mungbean-wheat rotation had the highest wheat grain yield (6.30–6.47 t ha−1) compared to other tillage systems in different crop rotation combinations. 相似文献
47.
为进一步开辟北京地区水产职业技能鉴定培训新的工作方法,探索长期有效地运行机制,通过对获得的信息进行综合分析,提出以农民田间学校为载体的培训新模式。 相似文献
48.
In order to quantify the influence of land use systems on the level of soil organic matter (SOM) to develop recommendations, long-term field studies are essential. Based on a crop rotation experiment which commenced in 1970, this paper investigated the impact of crop rotations involving increased proportions of sugar beet on SOM content. To this end, soil samples were taken in 2010 and 2012 from the following crop rotation sequences: sugar beet–sugar beet–winter wheat–winter wheat (SB–SB–WW–WW = 50%), sugar beet–sugar beet–sugar beet–winter wheat (SB–SB–SB–WW = 75%), sugar beet–grain maize (SB–GM = 50%) and sugar beet-monoculture (SB = 100%); these were analysed in terms of total organic carbon (TOC) and microbial biomass carbon (MBC) content, MBC/TOC ratio and the TOC stocks per hectare. In addition, humus balances were created (using the software REPRO, reference period 12 years) in order to calculate how well the soil was supplied with organic matter. In the field experiment, harvest by-products (WW and GM straw as well as SB leaves) were removed. After 41 years, no statistically significant differences were measured between the crop rotations for the parameters TOC, MBC, MBC/TOC ratio and the TOC stock per hectare. However, the calculated humus balance was significantly affected by the crop rotation. The calculated humus balance became increasingly negative in the order SB–SB–WW–WW, SB–SB–SB–WW, SB monoculture and SB–GM, and correlated with the soil parameters. The calculated humus balances for the reference period did not reflect the actual demand for organic matter by the crop rotations, but instead overestimated it. 相似文献
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