半干旱黄土丘陵区旱作农业高产综合耕作栽培技术探讨

本文根据多年的科学研究和生产实践，结合当地实际情况，浅析了旱作农业高产高效耕作栽培技术措施。     

Effects of sewage sludge amendment on humic acids and microbiological properties of a semiarid Mediterranean soil

The residual effects of adding 40 t ha^–1 sewage sludge (SL) to a degraded soil cropped with barley were investigated after 9 and 36 months in a field experiment under semiarid conditions. The principal soil properties were apparently still affected by SL amendment 9 months after application but the effects disappeared after 36 months. With respect to control soil humic acids (HAs), the SL-HA was characterized by higher contents of S- and N-containing groups, smaller contents of acidic groups, a prevalent aliphaticity, extended molecular heterogeneity, and smaller degrees of aromatic polycondensation and humification. Amendment with SL caused an increase in N, H, S and aliphaticity contents and a decrease in C/N ratios and O and acidic functional group contents in soil HAs isolated 9 months after SL application. These effects tended to decrease after 36 months, most probably because the slightly humified SL-HA was mineralised over time through extended microbial oxidation, while only the most recalcitrant components such as S-containing and aromatic structures were partially accumulated by incorporation into soil HA. Microbial biomass, basal respiration, metabolic quotient and enzymatic activities increased in soil 9 months after SL application, possibly because of increased soil microbial metabolism and enhanced mineralisation processes. After 36 months these properties returned to values similar to those of the unamended soil, presumably due to the loss of energy sources.     

半干旱区优良苜蓿品种试验示范

2001～2002年,研究了维可多,牧歌401,WL323,金皇后,阿尔冈金,巨人201,宁苜1号,晋南苜蓿等几个紫花苜蓿的物候期及生产性能。结果表明,维可多,牧歌401,WL323,金皇后等4个休眠级3级和4级的品种产草量高、再生性强,适宜太原地区大面积推广种植。     

Improvement of Wheat Water Use Efficiency in Semiarid Area of China

The greatest fear of global climate change is drought since in most areas where wheat is grownwater is the most important factor influencing wheat yield. Average wheat yield throughout the world is only30 -60% of the attainable yield potential because water shortage is the major factor preventing the realizationof maximum yield. Periods of drought alternating with short periods of available water are common conditionsto influence wheat productivity. Such conditions include variable frequency of dry and wet periods, intensityof drought, rate of drought onset and patterns of soil water deficit and/or atmospheric water deficit. It is thisdeficit and variable water conditions in semiarid environments that influence wheat productivity variously.This paper reviewed the physiological adaptation and benefits associated with deficit and variable water condi-tions. In addition, it also highlights the compensative effect of limited irrigation and breeding of new varietiesfor high water use efficiency (WUE) that could improve wheat productivity under water-limited environmentsin the semiarid regions. Considerable potential for further improvement in wheat WUE and productivity insemiarid environments seems to depend on effective conservation of moisture and effici ent use of this limitedwater such as soil fertility improvement, conservation tillage, residues and film mulch, rain water harvestingfor limited irrigation, and breeding for water saving varieties. Different crop, soil and water managementstrategies should be adjusted according to the conditions that prevail in various semiarid areas. By combiningsoil and water conservation approaches and adjusting the cropping system by growing drought-tolerant and wa-ter-saving cultivars, increase in wheat WUE and productivity could be achieved.     

Soil erosion and redistribution on cultivated and uncultivated land near las bardenas in the central Ebro river Basin,Spain

The semiarid regions of Spain, including the central part of the Ebro River basin, are under threat due to desertification. Severe erosion, as a result of poor land management, has led to degradation of the soil resource, and there is a clear need for quantitative erosion rate data to evaluate the problem. This study aimed to examine the potential for using caesium-137 to identify the patterns and rates of soil erosion and redistribution within this semiarid environment. Samples for the determination of caesium-137 were collected from uncultivated slopes and cultivated valley floor sites near the head and outlet of a small representative basin in the Las Bardenas area. The measured patterns of caesium-137 mobilization, redistribution and export provide a semiquantitative indication of the variation in erosion within the study site. Calibration of the caesium-137 measurements, taking account of the differing behaviour of radiocaesium on cultivated and uncultivated land, allows estimation of the actual rates of erosion and deposition involved. The results show (1) the erosion rates on the cultivated land (1.6–2.5 kg m⁻² yr⁻¹) are typically more than five times those seen on the uncultivated land (0.2–0.4 kg m⁻² yr⁻¹), and (2) erosion on the uncultivated land is significantly less severe at the head of the basin than at the outlet. Study of the vegetation cover suggests that lower growing shrubs and grasses may be more effective in reducing erosion in this environment than trees.     

Surface and subsurface organic carbon, microbial biomass and activity in a forest soil sequence

The distribution of organic carbon, microbial biomass and activity, from the surface down to 70 cm, was investigated through three semiarid Mediterranean soils: (1) a Typic Calcixeroll covered with a native pinewood (NP), (2) a Typic Calcixerept under a mature pine plantation (PP) on abandoned agricultural terraces and (3) a Typic Haploxerept under a grassland (GS). NP and GS had the highest and lowest soil organic carbon (SOC) pools, respectively. Both of them had decreasing SOC contents with depth. PP, which held intermediate SOC levels, showed an increase in total organic C and humic substances C with depth due to their mineralization in the anciently ploughed topsoil layer. The soils were similarly ranked as regards their microbial biomass and activity: NP>PP>GS. In general, the microbial communities were less dense and active towards the deeper horizons. More specifically, PP and GS had a very populated and active top 20-cm layer, which was attributed to the dense root system of their grass cover. NP maintained high microbial biomass and activity levels from 0 to 70 cm, progressively diminishing along with shrub root density (e.g. microbial biomass C dropped from 2342 to 394 mg kg⁻¹ soil). The latter soil presented the sharpest drop of its microbial properties with depth, what was considered an indicator of its quality. Generally decreasing patterns of microbial biomass and activity were not always coincident with previously published gradients of microbial metabolic abilities and genetic structure. This reinforces the need of combining biomass, activity and biodiversity measurements if the ecosystem's functioning is to be fully understood and a real monitoring of degradation processes and restoration strategies is to be achieved.     

REGULATING THE INDUSTRIAL STRUCTURE IS AN PRINCIPAL APPROACH TO THE ENVIONMENT ADMINISTRATION IN ARID AND SEMI-ARID AREAS

<正> 1. The crux of the environment administration problem is theeconomic development As we Know that the evolution of environment is not only due to Nature itself, but al-so to human being particularly. In the course of history, the Loess Plateau in China, oncewoody and rich in plants has now become a serious soil-erosion area on which lies thou-     

Coarse bed material patch evolution in low-order,ephemeral channels

In river channel beds composed of a wide range of grain sizes, the bed material is often arranged in discrete patches discernable by relative texture. These bed material patches are the primary source of entrainable coarse sediment within the channel system and their composition and size have been found to influence the composition and rate of sediment transport. Twelve coarse (gravel–cobble) sediment patches distributed throughout the channel network within a 4.53 ha watershed in southeastern Arizona were monitored for 2 years. Changes in patch area and grain size were measured and painted patch grains were monitored to confirm that patch grains were mobilized during flow. Individual coarse bed material patches exhibited variable persistence during flows with return frequencies ranging from approximately 1 year to 4.6 years. While no patch fully dispersed during the study period, two new patches formed. Most coarse patches remained relatively stable in area and grain-size distribution despite the entrainment of patch grains as lost grains were sufficiently replaced with sediment from upstream. Because of the grain replacement process and the effect of other sediment supply dynamics, the changes in patch area and grain-size distribution display a complex relationship with the magnitude of predicted grain mobilization within each patch. Results indicate that relative stability varies from patch to patch, influenced by the balance of patch grains transported out of the patch and the deposition of new grains into the patch. Predictive models of coarse sediment transport and yield that assume the channel bed is a fixed source of sediment supply may not adequately capture the sediment dynamics within patchy channel beds and should be used with caution when applied to these environments due to the possibility of patch instability as documented in this study.     

晋北半干旱风沙区长柄扁桃引种试验

在比长柄扁桃种源地更加寒冷、干旱的晋北半干旱风沙区开展长柄扁桃引种试验,结果表明,造林成活率在不浇水条件下达到91. 67%,苗木根系发育良好,新梢生长旺盛,实现了育苗技术本土化。长柄扁桃表现出优良的抗逆性,能够适应晋北半干旱风沙区的气候。     

半干旱区注水补灌对西葫芦产量及经济效益的影响

为最大限度地提高水分利用率,对半干旱区全膜双垄沟播种植西葫芦进行不同生长时期的注水补灌试验。结果表明:进行注水补灌后,西葫芦667 m~2增产14.07%~26.24%、增收536.55~984.17元,产量随着注水补灌次数增加而增加,以初瓜期+盛瓜期+中后期注水处理的产量最高(4 784.77 kg),净收益以初瓜期+盛瓜期注水处理的最好(5 532.58元)。