FAWN
发表于 2025-3-23 13:23:00
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云状
发表于 2025-3-23 15:43:21
https://doi.org/10.1007/978-3-642-78448-4ritive elements. These soils are an important resource in that much of the world’s grain and livestock are produced on them. The extensive agricultural development is a consequence of not only the general absence of forest cover, making conversion to agriculture relatively simple, but the natural fe
Panacea
发表于 2025-3-23 19:31:20
D. P. Landau,K. K. Mon,H.-B. Schüttlerall, by leguminous nitrogen fixation. Although animal wastes, nonsymbiotic fixation, and atmospheric deposition can be significant sources of N, a large fraction of the first can be traced to legume sources and the latter two are generally insufficient to maintain productivity of cropland. In the Me
木质
发表于 2025-3-23 22:28:27
Conference proceedings 19941st editionon to its fertilizing value, this organic material is likely to improve the soil physical condition. The gradual decrease in the organic matter content in cultivated soils, which may lead to deterioration of the soil physical status and erosion, is particularly worrying in warm areas, where organic
臭名昭著
发表于 2025-3-24 03:28:01
Complexity in Rayleigh-Bénard Convectioncrop production. Much of this land is best described as dryland. It is important to distinguish between dryland agriculture in particular and rain-fed agriculture in general. Clearly, they both exclude irrigation. The emphasis for rain-fed agriculture, however, is often on disposal of excess water,
不幸的人
发表于 2025-3-24 06:50:37
Advances in Soil Sciencehttp://image.papertrans.cn/a/image/149783.jpg
Obscure
发表于 2025-3-24 11:57:09
Advances in Soil Science978-1-4612-4790-6Series ISSN 0176-9340
确定的事
发表于 2025-3-24 15:09:17
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使入迷
发表于 2025-3-24 22:51:28
978-1-4612-9157-2Springer-Verlag New York Inc. 1987
神经
发表于 2025-3-25 01:42:38
0176-9340well to meeting the increased need for food and fiber. While the population growth during this period averaged almost 2% annually, the production of grain increased at an even faster rate. From 1950 to 1973, grain production increased 3. 1% annually, but slowed to about 2% from 1973 to 1984. There