首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   30篇
  免费   0篇
  30篇
  2018年   1篇
  2017年   1篇
  2016年   2篇
  2013年   2篇
  2012年   10篇
  2009年   1篇
  2008年   1篇
  2006年   1篇
  2005年   1篇
  2002年   1篇
  2001年   3篇
  1999年   1篇
  1997年   2篇
  1995年   1篇
  1994年   2篇
排序方式: 共有30条查询结果,搜索用时 31 毫秒
1.
Abstract. Continuous cultivation of soils of the semiarid tropics has led to significant land degradation. Soil erosion and nutrient loss caused by high runoff volumes have reduced crop yields and contributed to offsite damage. We compared a number of soil management practices (tillage, mulch and perennial/annual rotational based systems) for their potential to improve crop production and land resource protection in an Alfisol of the semiarid tropics of India. Runoff and soil erosion were monitored and surface soil and sediment were analysed for nitrogen and carbon to determine enrichment ratios. Amelioration of soils with organic additions (farmyard manure, rice straw) or rotating perennial pasture with annual crops increased soil carbon and nitrogen contents and reduced runoff, soil erosion and nutrient loss. Soil erosion totalled less than 7 t ha–1, but enrichment ratios were often greater than 2 resulting in up to 27 kg N ha–1 and 178 kg C ha–1 being lost in sediment. Up to an extra 250 mm of water per year infiltrated the soil with organic additions and was available for crop water use or percolation to groundwater. The results show that there are good opportunities for reducing degradation and increasing productivity on farms.  相似文献   
2.
Poultry manure (PM) has long been recognized the most desirable organic fertilizer. It improves soil fertility by adding both major and essential nutrients, as well as soil organic matter, which improves moisture and nutrient retention. The present study investigates the effectiveness of different levels of applied poultry-manure compost (PMC) and phospho-poultry-manure compost (PPMC) on the growth and yield of blackgram (Vigna mungo L). A field experiment was conducted to assess the nutrient-supplying capacity and soil health improvement potential of PMC and PPMC at 3.12, 6.25, 9.37, and 12.5 t/ha and to find the optimum dose of PMC as an organic fertilizer to maximize the pulse production in Alfisols of semi-arid tropics. Application of PPMC at 12.5 and 9.37 t ha?1 increased the seed yield 105% and 102% more than the no-manure plot. Application of PMC at 12.5 t ha?1 recorded 80% yield increment than no manure applied and the yield difference of PPMC was 20 to 25% greater than PMC alone. Application of PPMC at 12.5 and 9.37 t ha?1 resulted in desirable soil physical and chemical properties especially 85 and 70% soil-available P improvement and significant role in increasing yield of blackgram. Application of PPMC at 9.37 t ha?1 was found to be economically viable to the farmers in terms of improvement in soil properties and crop yield.  相似文献   
3.
Productivity of rainfed finger millet in semiarid tropical Alfisols is predominantly constrained by erratic rainfall, limited soil moisture, low soil fertility, and less fertilizer use by the poor farmers. In order to identify the efficient nutrient use treatment for ensuring higher yield, higher sustainability, and improved soil fertility, long term field experiments were conducted during 1984 to 2008 in a permanent site under rainfed semi-arid tropical Alfisol at Bangalore in Southern India. The experiment had two blocks—Farm Yard Manure (FYM) and Maize Residue (MR) with 5 fertilizer treatments, namely: control, FYM at 10 t ha?1, FYM at 10 t ha?1 + 50% NPK [nitrogen (N), phosphorus (P), potassium (K)], FYM at 10 t ha?1 + 100% NPK (50 kg N + 50 kg P + 25 kg K ha?1) and 100% NPK in FYM block; and control, MR at 5 t ha?1, MR at 5 t ha?1 + 50% NPK, MR at 5 t ha?1 + 100% NPK and 100% NPK in MR block. The treatments differed significantly from each other at p < 0.01 level of probability in influencing finger millet grain yield, soil N, P, and K in different years. Application of FYM at 10 t ha?1 + 100% NPK gave a significantly higher yield ranging from 1821 to 4552 kg ha?1 with a mean of 3167 kg ha?1 and variation of 22.7%, while application of maize residue at 5 t ha?1 + 100% NPK gave a yield of 593 to 4591 kg ha?1 with a mean of 2518 kg ha?1 and variation of 39.3% over years. In FYM block, FYM at 10 t ha?1 + 100% NPK gave a significantly higher organic carbon (0.45%), available N (204 kg ha?1), available P (68.6 kg ha?1), and available K (107 kg ha?1) over years. In maize residue block, application of MR at 5 t ha?1 + 100% NPK gave a significantly higher organic carbon (0.39%), available soil N (190 kg ha?1), available soil P (47.5 kg ha?1), and available soil K (86 kg ha?1). The regression model (1) of yield as a function of seasonal rainfall, organic carbon, and soil P and K nutrients gave a predictability in the range of 0.19 under FYM at 10 t ha?1 to 0.51 under 100% NPK in FYM block compared to 0.30 under 100% NPK to 0.67 under MR at 5 t ha?1 application in MR block. The regression model (2) of yield as a function of seasonal rainfall, soil N, P, and K nutrients gave a predictability in the range of 0.11 under FYM at 10 t ha?1 to 0.52 under 100% NPK in FYM block compared to 0.18 under MR at 5 t ha?1 + 50% NPK to 0.60 under MR at 5 t ha?1 application in MR block. An assessment of yield sustainability under different crop seasonal rainfall situations indicated that FYM at 10 t ha?1 + 100% NPK was efficient in FYM block with a maximum Sustainability Yield Index (SYI) of 41.4% in <500 mm, 64.7% in 500–750 mm, 60.2% in 750–1000 mm and 60.4% in 1000–1250 mm rainfall, while MR at 5 t ha?1 + 100% NPK was efficient with SYI of 29.6% in <500 mm, 50.2% in 500–750 mm, 40.6% in 750–1000 mm, and 39.7% in 1000–1250 mm rainfall in semi-arid Alfisols. Thus, the results obtained from these long term studies incurring huge expenditure provide very good conjunctive nutrient use options with good conformity for different rainfall situations of rainfed semiarid tropical Alfisol soils for ensuring higher finger millet yield, maintaining higher SYI, and maintaining improved soil fertility.  相似文献   
4.
The knowledge of profile distribution of soil organic carbon (SOC) in long‐term agricultural systems could help to store atmospheric carbon in the soil. We investigated profile distribution of easily oxidisable Walkley–Black SOC pool (SOCWB) under long‐term rice‐wheat (R‐W) and maize‐wheat (M‐W) cropping systems under soils of different pedogenesis. The soil samples were collected from the characteristic genetic horizons and analysed for carbon fractions. The SOCWB was the highest in soils under R‐W systems in both Alfisols and Inceptisols. The SOCWB stock in the deeper profile horizons under R‐W system was significantly (p < 0·05) higher than that under M‐W system especially in Typic Hapludalfs. Long‐term R‐W system could store on average 3·55 Mg ha−1 more SOCWB than M‐W system in the Ap horizon. The SOCWB stock in the Ap horizon of all pedons was significantly (p < 0·05) higher in Alfisols than that in Inceptisols. About 60–90% of the total profile SOCWB stock was contributed by B‐horizon because of its greater extent. Considering the whole profile, clay was negatively correlated with SOC fractions; however, the SOC fractions were closely related to each other. This study reveals that the distribution of SOCWB is different in long‐term R‐W and M‐W systems not only in surface but also in the deeper horizons and the magnitude of the variation is influenced by the specific pedogenic processes. This indicates the significance of profile SOCWB stock instead of topsoil SOCWB stock in quantifying carbon retention potential of the long‐term management practices. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
5.
Abstract. The restorative ability of herbaceous ( Psophocarpus palustris, Pueraria phaseoloides ) and woody ( Leucaena leucocephala, Senna siamea, Acacia leptocarpa, Acacia auriculiformis ) legume species and of natural regrowth was studied on an eroded and compacted Oxic Paleustalf in southwestern Nigeria. Compared to the control treatment that was continuously cropped for 15 years, four years of fallowing significantly improved test crop yields. However, fallowing with the above species did not substantially improve soil properties, particularly soil bulk density. A longer fallow period may be needed to amend soil physical conditions of this degraded Alfisol. Soil chemical properties were greatly improved following land clearing and plant biomass burning in 1993. However, the residual effect of burning on soil fertility was insignificant in the second cropping year. Among the fallow species, P. palustris and natural fallow showed the best residual effect on test crop performance. Despite the high biomass and nutrient yields of S. siamea and A. auriculiformis , test crop yields on these plots were low due to the border effects from the uncleared and fallowed subplots.  相似文献   
6.
A study was conducted at Hyderabad during 2009–11 to determine phosphorus (P) dose for ricerice and rice–sunflower. Available P increased when 100% recommended P dose (RDP) was applied. P applied to rice gave at par yield under 100 or 75% RDP. In rice–rice, grain yield of 5668 and 5775 kg ha?1 in kharif (5654 and 5760 kg ha?1 in rabi) were attained with P@75 and 100% RDP. Kharif P residual effect in rabi affected rice yield. P@100/75% RDP in kharif and rabi gave grain of 5916/5973 and straw 6230/6673 kg ha?1. P applied to sunflower revealed that yield was similar with 100 or 75% RDP. Sunflower yield was at par with P@100 or 75% RDP. 25% RDP in rice and sunflower may be reduced to attain similar yield of 100% RDP. In rice–rice, grain yield attained by 100% RDP in both seasons was 11.42t ha?1 yr?1, while 75% RDP gave yield of 11.45t ha?1yr?1.  相似文献   
7.
The hardsetting surface of many Alfisols in Australia is a limiting factor in crop production. Better soil management systems are required to improve productivity. This study reports the effects of several untested management systems, involving the combined effects of tillage (deep ripping (Rp), deep mouldboard ploughing (Mb) and disc ploughing (Disc)), irrigation layout (permanent beds, border ditch) and crop rotation treatments (single cropping (SC), double cropping (DC) and pasture (P)) on soil structure and the production of irrigated soybeans (Glycine max, L.) on a hardsetting Alfisol. It was conducted under a system of controlled traffic near Trangie, New South Wales, Australia. The DC and P treatments increased total water entry and soil organic carbon. Soybean leaf water potential (LWP) improved, and soybean yield was increased by as much as 58%. The retention of cereal and P stubble apparently enhanced total water entry by slowing the rate of irrigation water advance and by reducing the potential for slaking. The increases in soil water were associated with a reduction in soil strength; a key limiting factor in crop growth on hardsetting Alfisols. Deep tillage or the use of permanent beds did not affect soybean yields under the conditions reported in this paper, although the combination of disc ploughing and furrow irrigation was successful.  相似文献   
8.
Abstract. Topsoil (0–15 cm) bulk density, aggregate stability, soil dispersibility, water retention and infiltration were measured between 1989 and 1996 on an Alfisol under rehabilitation in southwestern Nigeria. The planted leguminous species were Pueraria phaseoloides, Senna siamea, Leucaena leucocephala, Acacia leptocarpa and A. auriculiformis. Also, plots with natural fallow and maize/cassava intercropping were included. Level (minimum) and mound tillage with hoes was adopted for the cultivated areas under study after 4 and 6 year fallow periods. Under fallow, the soil bulk density decreased from1.56 to 1.11 t m73.The continuously cropped treatment (level tillage) had significantly higher bulk density than the fallowed subplots after 6 years. Mean soil penetrometer resistance ranged from 75 to 157 kPa for fallowed plots and from 192 to 295 kPa for the continuously cropped (level tillage) subplot. Surface soilwater contentswere similar for all the treatments during the soil strength measurements. Although soil aggregates were generally of low stability and not well formed, they were improved by fallowing.
Soil structural improvement by planted fallows was similar to that by natural fallow, but the trees were more promising for long-term fallow (>6 years) than the herbaceous P. phaseoloides. However, the improvement in soil structure after 4 or 6 year fallow could not be maintained in subsequent cropping. Furthermore, the significant improvement in soil bulk density caused by A. auriculiformis and natural fallow was more rapidly lost on the cultivated subplots compared with other fallow treatments. Thus, soil structure recovery under a fallow does not imply a sustained improvement when stress is applied to this soil. Post-fallow soil management options such as residue incorporation and tillage to ameliorate compaction or soil strength will be necessary to enhance the improvements by fallow species.  相似文献   
9.
Sub-optimum production in pineapple fields in India is a common feature in Alfisols. The diagnosis and management of nutrient constraints assume a greater significance in maximizing production sustainability. DRIS norms were computed from the data bank of 324 sub-plots on leaf mineral composition, soil available nutrients, and corresponding mean yield representing three diverse pineapple belts for 3 seasons during 2002 –04. DRIS norms derived primarily from basal portion of ‘D'leaves sampled at 4th to 5th month suggested optimum leaf nutrient concentration viz. 1.21–1.85% nitrogen (N), 0.13–0.18% phosphorus (P), 1.19–1.62% potassium (K), 0.27–0.35% calcium (Ca), 0.43–0.56% magnesium (Mg), and 78.4–102.5 iron (Fe), 41.5–58.3 manganese (Mn), 7.4–10.2 copper (Cu), and 12.2–15.8 zinc (Zn) (ppm) in relation to fruit yield of 55–72 tons ha?1. Likewise, DRIS norms for soil fertility corresponding to similar level of fruit yield were determined. The norms were further observed validating the leaf/soil test values obtained from productive plots, suggesting the DRIS as a dynamic interpretation tool for diagnosis of nutrient constraints using both, leaf as well as soil analysis.  相似文献   
10.
Tillage-induced changes in soil quality are important to understanding soil strength and water retention and transmission properties. Thus, this study was conducted to assess the effects of two tillage systems under un-drained and drained conditions on tensile strength (TS) of 5–8 mm aggregates, soil water characteristics (SWC), plant available water (PAW), and the water infiltration rate (i). Soil properties were determined mainly in the surface (0–10 cm) layer on a Crosby (fine, mixed, mesic, Aeric Ochraqualf) silt loam soil at the Waterman Farm of the Ohio State University, Columbus, OH on a 14-year-old field study. Effect of two tillage treatments comprising no-tillage (NT) and conventional tillage (CT) were studied for two levels of drainage: un-drained (UD) and tile drained (D). The TS for 0–10 cm depth was significantly (P ≤ 0.01) affected by tillage and drainage treatments, and was higher in CT than NT by 61% in UD and by 48% in D soil. In comparison, TS increased by 13% in NT and 4% in CT in D compared with the UD treatments. Soil organic carbon (SOC) in 0–10 cm depth of NT–UD treatment was 23% higher than CT–UD treatment and 38% more than NT–D treatments. Tillage and drainage impact on SWC was non-significant at 0 kPa suction, but significant (P ≤ 0.1) at −3, −6, −10, −30, −100 and −300 kPa suctions indicating that water was retained more in NT–UD than CT–UD soil. The PAW was significantly influenced by drainage (P ≤ 0.01) but not by tillage treatments. Yet, there existed a general trend of about 8% more PAW in NT–UD than CT–UD treatments. In contrast, PAW was 48% more in soil from NT–UD than NT–D treatments. PAW increased with increase in the SOC concentration (R2 = 0.89; P ≤ 0.01). There were also differences in soil water sorptivity (S), and equilibrium infiltration rate (ic) in NT–UD compared with CT–UD treatments. A positive and significant correlation (r = 0.57, P ≤ 0.05) occurred between ic and SOC concentration. The value of S was more in NT–UD by 70% than CT–UD, and 46% in NT–D than CT–D. Similarly, the ic was more in NT than CT by 119% in UD compared with 82% in D soil. The value of A in NT was higher than that in CT by 39% and 12% in UD and D treatments, respectively. The mean cumulative infiltration (I) in 3 h was 71.4 cm in NT versus 44.0 cm in CT in UD compared with 62.1 cm in NT and 48.4 cm in CT for the D treatment. The I was positively and significantly correlated with SOC concentration (r = 0.32, n = 12, P ≤ 0.1) indicating improvement of I with increase in SOC concentration. Results of this study suggest that conversion from CT to NT management system may reduce the risk of surface runoff, increase soil aggregation, and improve soil hydrological properties.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号