[Effects of conservation tillage measures on soil water and NO-N leaching in dryland maize cropland].

Based on a field experiment on conservation tillage over 15 years in Weibei Highland maize cropland, six conservation tillage patterns, i.e., conventional tillage (CT), no-tillage (NT), no-tillage plus biochar (NB), no-tillage and straw mulching (NS), no-tillage and plastic film mulching (NF), and no-tillage and straw-plastic film mulching (NSF), were investigated for their effects on soil water and nitrate nitrogen(NO-N) leaching, to seek sustainable agricultural cultivation measures suitable for the region.

Effect of long-term fertilization on wheat yield under different precipitation patterns.

Rational application of nitrogen and phosphorus is one of the main pathways to enhance wheat yield. The optimum dosage of nitrogen and phosphorus used in different precipitation patterns was studied using the binary quadratic regression equation, which could provide a basis for fertilization of wheat in Loess Plateau. The results showed that the amount of nitrogen and phosphorus ferti-lizer required for the maximum yield was dependent on precipitation patterns.

[Effect of long-term fertilization on winter wheat yield from the dry land under different precipitation patterns].

Based on 30 years long-term fertilization experiment on the semiarid Loess Plateau in China, we studied the effect of different fertilizer treatments on the winter wheat yield, fertilizer contribution rate (FCR) and precipitation use efficiency (PUE) in different precipitation years (drought, normal and wet years). The result showed that the wheat yield, FCR and PUE were significantly higher in nitrogen + phosphorus (NP) and nitrogen + phosphorus +potassium (NPK) treatments than in control (CK) and phosphorus (P) treatments when winter wheat was planted for 30 consecutive years. The wheat yield, FCR and PUE in NPK treatment were highest, with values of 3480 kg·hm, 61.

[Effects of different re-vegetation patterns on soil organic carbon and total nitrogen in the wind-water erosion crisscross region, China].

This study was conducted to analyze the responses of soil organic carbon (SOC) and total nitrogen (TN) to three typical re-vegetation patterns, i.e., grassland, alfalfa land and peashrub land on the Loess Plateau of China, and also to assess the dynamics of SOC and TN with re-vegetation age.

[Effects of continuous cropping of wheat and alfalfa on soil enzyme activities and nutrients].

Based on a long-term rotation and fertilization experiment in Changwu, Shaanxi, China, we determined the enzymatic activities and nutrients in soils after 27 years continuous cropping of alfalfa and wheat, respectively. The activities of invertase, urease and phosphatase were not affected by fertilization treatment within each cropping system, but they were significantly higher in the alfalfa continuous cropping system than in the wheat continuous cropping system under each fertilization treatment. The activity of hydrogen peroxidase was not affected by the type of cropping system or fertilization treatment.

[Effects of long-term rotation on the nutritional quality of wheat grain protein on dryland of Loess Plateau, Northwest China].

A long-term experiment was conducted on the dryland of Loess Plateau to study the effects of three typical rotation systems, including wheat-sainfoin rotation, wheat-pea rotation, and wheat-maize rotation, on the nutritional quality of wheat grain protein. Rotation system and the cropping years of rotated plants affected the nutritional quality of wheat grain protein in varying degrees. As compared with continuous wheat cropping, wheat-sainfoin rotation made the nutritional quality of wheat grain protein relatively stable, and the essential amino acid content, amino acid score, amino acid ratio coefficient, chemical score, and amino acid index of the protein all relatively high, being able to be adopted as a cropping system to product high quality protein wheat in Loess Plateau.

[Coupling analysis of agro-ecolomic system in gully area of Loess Plateau in 1949-2008: a case study in Changwu County of Shaanxi Province].

Based on the analysis of the coercing and dynamic evolution relationships between agro-economic system and agro-ecological system, and by using modified entropy method, the weight of each evaluation index for the agro-ecolomic system in Changwu County of Shaanxi Province was determined, and, by employing coupling degree model, the coupling processes of agro-ecolomic system in the gullyarea of Loess Plateau were investigated. From 1949 to 2008, the agro-ecolomic system in the County experienced three stages of "traditional extensive agriculture", "agricultural mechanization", and "agricultural pre-modernization". In corresponding to the implement of national macro policies, the coupling degree of the agro-ecolomic system reached two peaks standing for utmost increasing phase and three valleys standing for coordinate development phase.

[Seasonal characteristics of soil respiration and affecting factors under typical vegetations in the water-wind erosion crisscross region of the Loess Plateau].

By the soil respiration system, the characteristics of soil respiration were investigated to explore the correlations between soil respiration and soil temperature, soil water and soil nutrient under different land use patterns in the water-wind erosion crisscross region of the Loess Plateau. The results indicated that the seasonal changing characteristics of soil respiration were distinguished significantly among different vegetations, and soil water content and temperature were the main influencing factors. Soil respiration seasonal changing ranges, such as bare land, crop land, Medicago sativa land, Caragana korshinskii land, abandoned wild grass land, Stipa bungeana land, wild grass land, degraded Medicago sativa land, sloping Medicago sativa land, sloping abandoned wild grass land, sloping crop land and terraced crop land, were 0.

[Effects of different patterns surface mulching on soil properties and fruit trees growth and yield in an apple orchard].

Taking a nine-year-old Fuji apple orchard in Loess Plateau as test object, this paper studied the effects of different patterns surface mulching (clean tillage, grass cover, plastic film mulch, straw mulch, and gravel mulch) on the soil properties and fruit trees growth and yield in this orchard. Grass cover induced the lowest differentiation of soil moisture profile, while gravel mulch induced the highest one. In treatment gravel mulch, the soil moisture content in apple trees root zone was the highest, which meant that there was more water available to apple trees.