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71.
蚯蚓对改良土壤和改善农业生态环境的作用 总被引：5，自引：0，他引：5
蚯蚓对土壤的耕耘比犁耕更有效,加强土壤通气;提供有益细菌,将土壤中的氨转化成为便于农作物吸收利用的形态;有助于将土壤中各种复合分子分解成为植物根系能够利用的成分。蚯蚓及时将地面残留的落叶枯草裂解转化为对土壤和植物的营养物质,可处理动物粪便以及城市垃圾,对有机农业和生态农业都有重要意义。 相似文献
72.
Soil carbon release along a gradient of physical disturbance in a harvested northern hardwood forest
Changes in soil respiration associated with forest harvest could increase net loss of CO2 to the atmosphere relative to pre-harvest values. By excavating quantitative soil pits across a gradient of physical disturbance in a harvested northern hardwood forest, this study examines C release from mineral soil. Mineral soil samples were analyzed for pH, percent organic matter (%OM), C and N concentration, δ13C, and total C per unit area. Results show a relationship between degree of disturbance and C concentration in soil 10-30 cm beneath the O-horizon. Highly disturbed sites show C depletion, with horizons from disturbed sites containing 25% less total C than the least disturbed sites. δ13C signatures of soil profiles at these sites show vertical mixing of plant-derived material into deeper mineral horizons. Mixing, as a result of physical disturbance, could have led to the observed C depletion by physical or chemical destabilization, or through the promotion of microbial respiration in deep mineral soil. Regardless of the mechanism, these results suggest elevated CO2 emissions from soil following harvest, and, thus, have implications for the validity of wood biomass as a carbon neutral energy source. 相似文献
73.
Hideo Kubotera 《Soil Science and Plant Nutrition》2020,66(1):15-20
ABSTRACT Soils in the Kyushu Okinawa region with problematic properties for agriculture were studied and the following findings were obtained. 1) Mahji-soils in Nansei Islands became very hard with desiccation under high-pH conditions; therefore, soil treatments that cause alkalinization such as overliming should be avoided. 2) In contrast to the generally favorable effects of organic matter on the physical properties of soil, the application of manure compost at 100 Mg ha?1 to Mahji-soils increased the degree of hardening with desiccation. 3) Application of clinker ash (coarse fraction of coal ash) at 10% (wt/wt) mitigated the hardening and shrinkage of Jagaru, a heavy-textured gray soil found on Nansei Island. 4) Non-allophanic surface horizons with strong acidity were widely distributed in the Andosol area of central Kyushu, covering at least 340 km2. These horizons showed a relatively large ratio of carbon per Alp (pyrophosphate extractable aluminum) and high content of allophane, and began forming around 2500 years ago. 5)Some Andosols in Kyushu showed remarkable hardness. They are divided into two types, according to the degree of weathering and hardening characteristics, and the different measures required to improve each type. 6) An experimental method for determining nitrate retention by soils was developed, and factors influencing the nitrate retention of Andosols were elucidated using this method. 7) A method for micromorphological observation of pelletized manure compost (PC) grains was developed. This method revealed that the internal microstructure of PC did not change in 18 months after compost application, whereas the volume of the grains decreased with the formation of voids around them. 8) As an indicator of soil acidity concerning the countermeasure for common scab, pH(KCl) can easily be used instead of exchangeable acidity y1, which is laborious to determine. The maximally simplified pH(KCl) measurement method can be carried out by farmers in the field. 相似文献
74.
Effects of soil freezing on nitrogen (N) mineralization have been the subject of increased attention in the ecological literature, though fewer studies have examined N mineralization responses to successive mild freezing, severe freezing and cyclic freeze–thaw events. Even less is known about relationships of responses to soil N status. This study measured soil N mineralization and nitrification in the field along an experimental N gradient in a grassland of northern China during the dormant season (October 2005–April 2006), a period in which freezing naturally occurs. Net N mineralization exhibited great temporal variability, with nitrification being the predominant N transformation process. Soil microbial biomass C and N and extractable NH4 + pools declined by 40, 52, and 56%, respectively, in April 2006, compared with their initial concentrations in October 2005; soil NO3– pools increased by 84%. Temporal patterns of N mineralization were correlated with soil microbial biomass C and N. N mineralization and nitrification increased linearly with added N. Microbial biomass C in treated soils increased by 10% relative to controls, whereas microbial N declined by 9%. Results further suggest that freezing events greatly alter soil N dynamics in the dormant season at this site, with considerable available N accumulating during this period. 相似文献
75.
Improving the soil environment for seedling emergence and plant growth is possible using a good tillage system. From March 1993 until June 1994, the effect of tillage system and plant residue incorporation practices on the bulk density and the soil strength of the surface layer of a vertisol (very fine, smectitic, thermic, chromic Haploxerert), on a less than 1 % slope, was investigated. The two tillage methods were moldboard (T1) and chisel (T2). The two plant residue incorporation dates were in August (R1) and in October (R2). Results indicated that R1 gave significantly higher bulk density than R2, while the different tillage treatments had no significant effect. Soil strength was significantly lower under T1 and R2 than under the other treatments. 相似文献
76.
77.
78.
M. Necpálová D. Li G. Lanigan I. A. Casey W. Burchill J. Humphreys 《Grass and Forage Science》2014,69(4):611-624
This study investigated changes in soil organic carbon (SOC) in a poorly drained clay loam soil under (i) permanent grassland (PG) over 7 years and (ii) after PG renovation over 2·5 years. The experimental area was divided into four blocks with four paddocks per block. Composite soil samples from each PG block were taken to 30‐cm depth on five occasions between 2004 and 2011. In June 2008, one paddock per block was renovated by ploughing and reseeding and sampled as above on the latter four occasions. Renovation decreased SOC (P < 0·05) by 32·2 t ha?1 in the 2·5 years following ploughing; the difference developed almost entirely (86%) in the first four months. Renovation had no effect on above‐ground productivity, standing root and stubble phytomass or on dissolved organic matter leaching. Therefore, soil respiration was considered to be a single potential pathway responsible for the SOC loss from renovated grassland. Although a simple linear regression indicated a tendency for PG to accumulate SOC, there was no evidence of recovery in SOC to previous levels following renovation during the study period. These results could have implications for greenhouse gas inventories in countries where PG is an important land‐use type. 相似文献
79.
Yellow mosaic disease (YMD) of black gram is an important production constraint in India. Black gram germplasm, consisting of 344 accessions, originally collected from different geographic regions of India and conserved in National Gene Bank at National Bureau of Plant Genetic Resources, India, were evaluated for their response against YMD. None of the accessions tested was found to be immune, however, considerable variation in disease response was observed among them. Of the 344 accessions, 32 showed resistance in the field during the rainy season (June–September) 2010 as assessed by coefficient of infection (CI) and area under disease progress curve (AUDPC). These accessions were re-evaluated during rainy season (June–September) 2011 and 2012 for their disease resistance along with yield-associated characters. Eight accessions that exhibited consistently highly resistant (HR) or resistant (R) reaction (CI ≤ 9) along with lower AUDPC value (≤650), were further evaluated following inoculation with whiteflies or via agroinoculation. Along with the resistant trait, these eight accessions were also found either similar or even better in their yield potential as compared to check. After artificial inoculation using viruliferous whiteflies under glasshouse, of the eight field-resistant accessions, response of two (IC144901 and IC001572) were categorized as HR as <10% plants exhibited minute yellow specks after 17–22 dpi. Two accessions viz. IC011613 and IC485638 showed <20% incidence with bright yellow specks or spots after 15–20 dpi and were grouped into R category. The resistance of these four accessions was further confirmed through agroinoculation of the infectious cloned viral DNA under controlled conditions. In resistant accessions low accumulation of viral DNA was observed over a period of time. These four accessions could be used in future breeding programmes to develop black gram cultivars resistant to YMD or could be used directly as varieties to manage YMD after adaption to various agro-climatic regions. 相似文献
80.
在研究二苯碳酰二肼测定铬的反应机理的同时,对使用同一消化浪测定土样中铬和钛的可行洼进行了试验,结果认为,采用H_2SO_4—H_3PO_4—HNP_3体系消化土壤样品,消化液可分别用二苯碳酰二肼比色法测铬和用二安替比林甲烷比色法测钛。经对全国不同地区的五个土样用本法与常规测铬法的对照试验,得到一致的结果。作者还发现,使用不同纯度级的二苯碳酰二肼得到不同的结果,认为必须使用分析纯级以上的试剂。 根据对络台物的可见一紫外吸收光谱的研究和其他试验结果,并结合前入的电泳试验等结果,阐述了二苯碳酰二肼测定铬的反应机理。 相似文献