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1.
R. Neil Sampson 《Water, air, and soil pollution》1993,70(1-4):519-532
There are a variety of opportunities to change land and forest management and, at the same time, create a positive impact on the current use of fossil energy. To the extent that these opportunities can be captured, they address the root cause of greenhouse warming-fossil fuel emissions-while, at the same time, improving economic opportunities, ecosystem productivity, and environmental conditions over broad areas. The need for better markets to absorb biomass energy, plus research to make biomass conversion more efficient, is probably the most important deterrent to achieving these possibilities. 相似文献
2.
Carin Tyler 《Biological conservation》1984,30(1):69-89
A report written in the Swedish language has been abridged and rewritten for foreign readers. Each calcareous fen site is a unique feature though it is possible to generalise such fens into five types according to soil type and most frequent plant communities. Previously most fen sites were used for hay and/or grazing, which gradually decreased from the middle of the 19th century and, since the 1950s has become very unusual. The effects of different management practices are still insufficiently known, observations on species are often contradictory and hence experimental studies are needed. The future management should be adjusted to the sensitivity of each site, the fen type, the main plant communities and the purposes of the preservation. 相似文献
3.
V. I. Kiryushin 《Eurasian Soil Science》2006,39(11):1157-1163
The acceptance of the biospheric paradigm of nature management anticipated by V.V. Dokuchaev instead of the anthropocentric ideology suggests a solution of problems related to the ecologization of agriculture and its adaptive intensification under the conservation of soil ecological functions. The landscape-ecological principles of human economic activity proposed by Dokuchaev have developed into the modern methodology of agrolandscape design and adaptive-landscape farming. 相似文献
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5.
《Communications in Soil Science and Plant Analysis》2012,43(19-20):2969-2985
Abstract Research is needed to compare the different techniques for developing site‐specific phosphorus (P) recommendations on a field‐wide basis. The objective of this study was to determine the impact different techniques for developing site‐specific P recommendation maps on yield and profitability. Enterprise analysis combined with a crop simulation model and detailed field characterization was used to estimate the value of spatial P information in a system where N was not limiting. The systems evaluated were continuous corn (Zea mays) and corn and soybean (Gfycine max) rotations where sampling and fertilizer applications were applied annually and semi‐annually, respectively. The sampling techniques tested were: (i) an unfertilized P control; (ii) whole field; (iii) whole field plus historic information (feedlot); (iv) landscape positions; (v) soil type; (vi) soil type plus historic information (feedlot); and (vii) 90‐m grid sampling. The finding of this study were based on soil samples collected from a 30 by 30‐m grid. The value of the spatial information was dependent on the crops response to P, the accuracy of the different sampling techniques, crop rotation, and the length of time between sampling dates. All of the sampling techniques produced different application maps. The recommendation map based on a single composite sample under fertilized 56.5% of the field. Increasing the sampling density reduced the percentage of under‐fertilized land. If corn had a low P response, then simulation/enterprise analysis indicated that applying P did not increased profits. For all scenarios tested: (i) the soil type + historic sampling approach had higher potential profits than the 90 m grid sampling approach; and (ii) there was no economic benefit associated with the 90‐m grid sampling. However, if research shows that amortization of sampling and analysis costs over 3 or 4 years is appropriate, then it may be possible to derive economic benefit from a 90‐m grid sampling. For a corn/soybean rotation, where fertilizer was applied when corn was planted and N and P was not applied to soybeans, enterprise/ simulation analysis (2.8 Mg ha‐1 soybean yield goal and a moderate P model) showed that soil + historic sampling approach increased profitability $3.74 ha‐1 when compared to the uniform P treatment. 相似文献
6.
Adaptive management principles and sediment management 总被引：3，自引：3，他引：0
Sabine E. Apitz 《Journal of Soils and Sediments》2008,8(6):359-362
8.
Pradheep K. Latha M. Nayar E. Roshini Bhat K. V. 《Genetic Resources and Crop Evolution》2022,69(3):939-948
Genetic Resources and Crop Evolution - Correcting taxonomic misidentifications is crucial to ensuring the conservation and use of wild relatives in crop breeding programmes. Macrotyloma... 相似文献
9.
《Geoderma》2007,137(3-4):327-339
Our objectives were to describe the field-scale horizontal and vertical spatial variability of soil physical properties and their relations to soil map units in typical southeastern USA coastal plain soils, and to identify the soil properties, or clusters of properties, that defined most of the variability within the field. The study was conducted on a 12-ha field in Kinston, NC. A 1:2400 scale soil survey had delineated three soil map units in the field: Norfolk loamy sand, Goldsboro loamy sand, and Lynchburg sandy loam. These are representative of millions of hectares of farmland in the Coastal Plain of the southeastern USA. Sixty soil cores were taken to ∼ 1-m depth, sectioned into five depth increments, and analyzed for: soil texture as percentage sand, silt, and clay; soil water content (SWC) at − 33 and − 1500 kPa; plant available water (PAW); saturated hydraulic conductivity (Ksat); bulk density (BD); and total porosity. A penetrometer was used to measure cone index (CI) at each sample location. Variography, two mixed-model analyses, and principal components analysis were conducted. Results indicated that soil physical properties could be divided into two categories. The first category described the majority of the within-field variability and included particle size distribution (soil texture), SWC, PAW, and CI. These characteristics showed horizontal spatial structure that was captured by soil map units and especially by the division between sandy loams and finer loam soils. The second class of variables included BD, total porosity, and Ksat. These properties were not spatially correlated in the field and were unrelated to soil map unit. These findings support the hypothesis that coastal plain soil map units that delineate boundaries between sandy loams versus finer loam soils may be useful for developing management zones for site-specific crop management. 相似文献
10.
《Soil & Tillage Research》1987,9(1):65-77
Field experiments were conducted on a silty clay loam soil during 1980–1981 and 1981–1982 to study the effect of different soil management practices, such as zero cultivation (ZC), conventional cultivation (CC), CC + surface-applied pine needle mulch at a rate of 10 t ha−1 (CC + M), deep ploughing (DP) and inter-row compaction (IRC), on the soil hydro-thermal regime and root growth of wheat (Triticum aestivum L.). The soil of the experimental site is classified as Alfisol, Typic Hapludalf in which compact sub-surface layers are encountered. In the CC + M treatment, the soil water potential in the sub-surface layers remained higher in comparison to other treatments. In the DP treatment, the decrease in soil water potential was observed to greater depths in comparison to the remaining treatments. The soil water flux at 60-cm depth, calculated during 150–173 days of crop growth, was always upward in the CC + M treatment, at a rate varying from 0.2 to 1.16 cm day−1. In the other treatments, the flux at this depth was first downward then it became upward. The upward flux was highest under the DP treatment, followed by CC and CC + M and least under IRC and ZC treatments. The minimum temperature under CC + M treatment at 10-cm depth was raised by 4°C over the temperature under CC treatment (5°C). The rooting density and length in the CC + M treatment were the highest, followed by DP treatment, in comparison to the remaining treatments. 相似文献
11.
Abstract. In the Sahel, promising technologies for agricultural intensification include millet stover mulching and ridging. A four year on‐farm experiment was set‐up in order to assess the effect of various combinations of these two technologies on crop development and yield in a millet (Pennisetum glaucum (L.) R. Br.) ‐ cowpea (Vigna unguiculata (L.) Walp.) intercropping system. Treatments included bare surface, ridging, a surface applied banded millet stover mulch (2 t ha–1) and a banded millet stover mulch (2 t ha–1) buried in ridges. The latter three treatments were implemented exclusively in the cowpea rows, with an annual rotation between the millet and cowpea rows. On bare and ridged plots, millet yields fell below 100 kg grain ha–1 after the first year. This was ascribed mainly to soil acidification and loss of soil organic matter rather than to soil physical constraints or water availability despite extensive surface crusting and high soil penetration resistance and bulk density. Compared to the bare plots, ridging increased cowpea hay production by 330% over the four years which was attributed to lower soil penetration resistance and bulk density but also to a reduction of 0.15 cmol+ kg–1 exchangeable acidity in the ridges. Except during the severe drought year of 1997, millet grain yield in the banded mulch treatment remained fairly stable over time at 526 ± 9 kg ha–1. However, a detailed analysis revealed yield compensation mechanisms between various yield components depending on the timing of occurrence of the abiotic stresses. Cowpea productivity was always higher in buried banded mulch plots than in surface applied banded mulch plots but the former treatment appeared unable to sustain millet yields. This decline was attributed to a greater nutrient uptake by cowpea and more rapid acidification in the buried mulch treatment compared to the banded mulch treatment. 相似文献
12.
BBS是现代社会大多数网站提供的供用户发表看法与交流信息的一个重要途径,本文介绍了网上论坛管理系统的开发平台及工具选择、数据库设计、代码设计以及系统开发过程中所运用的关键技术。 相似文献
13.
本文简要分析了我国农村地区电子商务管理的现状，指出了其中存在的不足，说明运用信息技术对农村电子商务进行数字化管理是解决我国目前农村地区电子商务缺失和促进我国农村数字化管理水平的重要途径之一。介绍了农村电子商务信息管理系统的建立条件、设计思路、技术路线及实现功能，并讨论了我国农村电子商务的发展应用前景。 相似文献
14.
Abstract. In the Sahel, promising technologies for agricultural intensification include millet stover mulching and ridging. A four year on-farm experiment was set-up in order to assess the effect of various combinations of these two technologies on soil chemical and physical quality in a millet ( Pennisetum glaucum (L.) R. Br.) –- cowpea ( Vigna unguiculata (L.) Walp.) relay intercropping system. Treatments included bare surface, ridging, a surface applied banded millet stover mulch (2 t ha–1 ) and a banded millet stover mulch (2 t ha–1 ) buried in ridges. The latter three treatments were implemented exclusively in the cowpea rows, with an annual rotation between the millet and cowpea rows. Both the bare and ridge plots experienced a rapid loss of organic carbon, acidification and the development of extensive surface crusts but no increase in bulk density or penetration resistance. In the year of application, mulching improved soil quality in the cowpea row with respect to pH, organic carbon and exchangeable K+ and Mg++ content, penetration resistance and bulk density, and it reduced the decline in exchangeable Ca++ and total N content. In the year following mulch application, a general decline in soil chemical quality was observed in the millet row, except for organic carbon content, and a positive residual effect was observed on penetration resistance and bulk density. As a rule, the effects of mulching in the year of application tended to be stronger in the ridged treatment with buried residue than in the banded surface mulch. In the year following application, this tendency was reversed. For the purpose of reducing soil degradation by nutrient mining and wind erosion, a banded surface mulch therefore appeared more effective than buried mulch. 相似文献
15.
Paleosolic features are important to land use and management of soils on fan terraces in southwestern Oregon. Soil-geomorphology studies identified relict duripans and established the distribution of associated Durochrepts, Duraquolls and Argixerolls. These soils represent two late Pleistocene geomorphic surfaces, each with distinct kinds of periglacial patterned ground. Soil behavior is discussed in terms of soil characteristics and qualities and compared for cropland, grazing, construction, and waste disposal. 相似文献
16.
Matshwene Moshia Raj Khosla Dwayne Westfall Jessica Davis Robin Reich 《Journal of plant nutrition》2016,39(1):59-70
Precise quantification of nitrogen (N) mineralization in animal manure from different productivity-level management zones (MZs) could result in efficient and safe utilization of manure as N fertilizer. The objective of this study was to compare N mineralization rates of dairy cattle manure within and across three productivity-level MZs. To accomplish this, a 120 day laboratory incubation study was conducted at the Natural Resources Ecology Laboratory at Colorado State University using a completely randomized design set as a 2 factor factorial. Treatments for the study, which included the field equivalent of, 22, 44, 67, and 134 Mg ha?1 of applied animal manure, were replicated four times. Soils used in the study were collected from the top 15 cm of high, medium and low MZs from Fort Collins, Colorado, USA on a continuous corn (Zea mays L.) field. A significant difference (P ≤ 0.05) in mineralized N across MZs was found across manure rates. The high, medium and low MZ N mineralization rates were compared and there was no significant difference in cumulative N mineralized between MZs over time. The lack of statistical difference in mineralized N between MZs is hypothesized to have been influenced by the lack of substantial difference in soil pH and particle sizes (only 6% clay difference between MZs). That being the case, a study involving spatially variable soils with significantly different soil particle size between MZs may result in a different conclusion. The results of the study support the hypothesis that variable rates of manure mineralize differently within MZs; however, the results do not support the hypothesis that variable rates of manure in soil may mineralize differently across MZs. 相似文献
17.
Mary V. Ashley Mary F. Willson Dennis J. O'Dowd Joel S. Brown 《Biological conservation》2003,111(2):115-123
Here we review growing evidence that microevolutionary changes may often be rapid and, in many cases, occur on time frames comparable to human disturbance and anthropogenic change. Contemporary evolutionary change has been documented in relatively pristine habitats, in disturbed populations, under captive management, and in association with both intentional and inadvertent introductions. We argue that evolutionary thinking is thus relevant to conservation biology and resource management but has received insufficient consideration. Ignoring evolution may have a variety of consequences, including unpredicted evolutionary responses to disturbance and naive or inappropriate management decisions. Philosophically, we must also grapple with the issue of whether the evolution of adaptations to disturbance and degraded habitats is sometimes beneficial or something to be rigorously avoided. We advocate promoting evolutionarily enlightened management [Lecture Notes in Biomathematics 99 (1994) 248], in which both the ecological and evolutionary consequences of resource management decisions are considered. 相似文献
18.
本文基于ASP.NET的设计思想和实现方法,结合ADO.NET的应用,设计并实现一个随书光盘管理系统,旨在探讨用ASP.NET技术开发实现信息管理系统的方法与途径。 相似文献
19.
《Agricultural and Forest Meteorology》1988,43(1):71-82
Little is known of the microclimate differences in orchards posed by different floor management systems. Comparisons were made of microclimatic factors on eight radiation frost nights in the spring of 1986 between two adjacent 1.4 ha peach (Prunus persica (l.) Batsch) plots in the Shenandoah Valley of West Virginia. The two plots were under different floor management systems; one plot with a complete grass cover (grass plot) and the other plot consisted of alternating 3-m-wide soil, 3-m-wide grass strips with coal dust applied to the soil strip of the tree row (coal dust plot). The net radiative flux (Rn) on radiation frost nights from the coal dust plot was 10–15 W m−2 lower (greater radiative loss) than from the grass plot. Only 50% of this Rn difference in the early morning hours at the beginning of this study was accounted for by the soil heat flux (G) difference. However, G accounted for an increased percentage of the Rn difference in the early morning hours as the study progressed, reaching 100% at approximately 30 days from the commencement of this study. Differences of 0.5 and 1°C were found in bud and air temperatures, respectively, between plots, with bud temperature differences predicted by the Landsberg et al. model agreeing well with measured differences. Because the differences in Rn and G were nearly equal during radiation frost nights, it is apparent that little of the energy liberated by the soil was intercepted by the canopy. Provided a means of trapping the energy from the soil in the canopy can be devised, a potential 2–3°C difference in canopy temperature may be realized between these floor management systems for the site studied. These differences in canopy temperature, however, would be site-specific due to the effect of aspect, slope, relative position on slope, and vegetation on solar energy partitioning. A greater potential in utilizing soil management for frost protection may exist in other regions where orchard floors are devoid of vegetation and the soil treated area can be expanded. 相似文献
20.
P. A. Kozhevin 《Moscow University Soil Science Bulletin》2011,66(1):42-44
Several problems of soil biotechnology and their relation with global ecological problems are considered. An analysis of the
principal opportunities for soil biota management shows that scientific progress in this field is a necessary but insufficient
condition for the solution of these global problems. 相似文献