Phosphorus availability and farm structural factors: examining scarcity and oversupply in north‐east Germany

Assessing factors influencing phosphorus (P) availability in soils is important in preventing its overexploitation and excessive application in agricultural systems. Despite high historical P applications in the federal state of Brandenburg (Germany), county data on soil test P (STP) reveal considerable disparities in soil available P. In addition, negative soil balances as a result of small mineral P and manure inputs have been observed, raising questions about the factors leading to this situation. Our work focused on identifying possible causes operating at the farm management level by conducting a letter survey in two administrative districts of Brandenburg, the counties Barnim and Uckermark, linking farm management factors (ownership type, farm size, land tenure, animal husbandry with or without grassland and its intensity, presence of a biogas plant and organic production) to farmers’ self‐indicated levels of STP. Small‐ to medium‐sized individual farms tended to have (very) high STP, while large partnership farms and companies/cooperatives were sensitive to factors resulting in low STP. Farms with low shares of land ownership, the presence of grassland, extensive cattle farming and stockless organic farming had lower STP. On the other hand, biogas plants, partly in combination with intensive livestock (cattle) farming, were associated with larger STP. It was concluded that more care should be devoted to the design of agricultural policies and that further (inter‐ and transdisciplinary) research on this topic is needed.     

油草混播种类对油菜生产和草地生产性能的影响

为筛选与门源油菜混播效益最高的牧草种类,解决油菜连作障碍问题,提高青藏高原高海拔区土地的生产能力,本研究采用油菜混播箭筈豌豆、青稞和燕麦的方式,分时段取样,探究了油菜混播不同牧草对在不同时段牧草自身生产能力的影响,并通过土地当量比判断各混播组合的优劣。研究表明油菜-燕麦混播处理在7月6日时表现干重最高,单位面积达174.48 g；在7月21日表现为鲜重和鲜干比最高,在8月15日时表现为株高显著高于单作油菜(p＜0.05),较单作油菜高97.02%；鲜重最高,达2817.00 g。在9月11日,油菜-青稞和油菜-燕麦混播处理的株高显著高于单作油菜(p＜0.05),分别较单作油菜高64.33%和99.68%,以油菜-青稞混播处理的干重最高,达589.00 g,较单作油菜处理高147.51%。油菜-箭筈豌豆混播和油菜-燕麦混播有产量优势,油菜-燕麦混播的土地当量比最高,为1.11,土地利用效果最好。     

广东省农地边际化特征及其影响因素的地理探测

为了明确经济发达地区广东省农地边际化现象及其主要影响因素。本研究采用“单位成本纯收益指标”、“农地利用集约度指标”和“农作物播种面积指标”三大主要指标,对广东省2000—2015年农地边际化特征进行提取。选择影响农地边际化特征的19个因子,利用地理探测器方法对农地边际化现象的核心影响因素进行挖掘。结果表明：2000—2015年广东省共发生3次比较明显的农地边际化现象,分别在2001—2002年、2005—2006年、2010—2013年,且第3次边际化持续时间最长,情况最严重。社会经济发展水平与结构指标和农户家庭资源要素结构变化指标对农地边际化的影响程度较大,其中第三产业产值比重、农村农户固定资产投资、粮食总播种面积对农地边际化现象有较强的解释力,q值分别为0.8067、0.8055、0.7916。任何两因子相互交互作用都能增强对农地边际化现象的解释力。     

山西省高速公路集约用地评价

对高速公路用地进行集约用地评价,可以为未来区域土地利用提供决策依据。从高速公路的用地结构、用地功能和与外部因素的协调性出发,对山西高速公路建设用地的集约利用程度作出评价。结果表明:2001~2010年,山西省高速公路用地数量有所增长,其结构不断调整,功能不断增强,与人口、社会经济的协调性也不断加强,集约度不断提高。未来10年,山西省高速公路将迅速发展,必须加大集约利用力度,以尽可能少的用地满足人类社会发展对公路交通运输的需求。     

砂田甜瓜套作向日葵系统的养分利用研究

2010—2013年在庄浪县进行的砂田甜瓜套作向日葵系统的养分利用研究的结果表明,无论在甜瓜的初花期、座果期、膨大期套作食葵或油葵,套作系统比单作明显提高了作物的吸氮量、吸磷量和吸钾量。氮吸收量比单作增加50%~59%,磷吸收量比单作增加12%~41%,钾吸收量比单作增加33%~68%。     

广西鹿寨县耕地质量等别调查与评价

以鹿寨县为列,介绍了广西自治区县级耕地质量等别评价方法,详细分析了耕地质量等别评价结果,揭示了鹿寨县耕地质量等别结构和空间分布规律。     

建设用地集约利用评价指标的权重确定方法研究

基于建设用地集约利用评价指标,应用文献统计法和综合分析法,阐述了中国建设用地及建设用地集约利用评价指标权重赋权方法的现状,着重研究了各种权重确定方法在建设用地集约评价中的实践应用,并对其进行总结和讨论,探讨了建设用地集约利用评价指标权重确定方法的发展趋势.     

Monitoring desertification processes in Mongolian Plateau using MODIS tasseled cap transformation and TGSI time series

Most remote sensing studies assess the desertification using vegetation monitoring method. But it has the insufficient precision of vegetation monitoring for the limited vegetation cover of the desertification region. Therefore, it offers an alternative approach for the desertification research to assess sand dune and sandy land change using remote sensing in the desertification region. In this study, the indices derived from the well-known tasseled cap transformation(TCT), tasseled cap angle(TCA),disturbance index(DI), process indicator(PI), and topsoil grain size index(TGSI) were integrated to monitor and assess the desertification at the thirteen study sites including sand dunes and sandy lands distributed in the Mongolian Plateau(MP) from 2000 to 2015. A decision tree was used to classify the desertification on a regional scale. The average overall accuracy of 2000, 2005, 2010 and 2015 desertification classification was higher than 90%. Results from this study indicated that integration of the advantages of TCA, DI and TGSI could better assess the desertification. During the last 16 years, Badain Jaran Desert, Tengger Desert, and Ulan Buh Desert showed a relative stabilization. Otindag Sandy Land and the deserts of Khar Nuur, Ereen Nuur, Tsagan Nuur, Khongoryn Els, Hobq, and Mu Us showed a slow increasing of desertification, whereas Bayan Gobi, Horqin and Hulun Buir sandy lands showed a slow decreasing of desertification. Compared with the other 11 sites, the fine sand dunes occupied the majority of the Tengger Desert, and the coarse sandy land occupied the majority of the Horqin Sandy Land. Our findings on a three or four years' periodical fluctuated changes in the desertification may possibly reflect changing precipitation and soil moisture in the MP. Further work to link the TCA, DI,TGSI, and PI values with the desertification characteristics is recommended to set the thresholds and improve the assessment accuracy with field investigation.     

Maize/peanut intercropping increases photosynthetic characteristics, ~(13)C-photosynthate distribution,and grain yield of summer maize

Intercropping is used widely by smallholder farmers in developing countries to increase land productivity and profitability. We conducted a maize/peanut intercropping experiment in the 2015 and 2016 growing seasons in Shandong, China. Treatments included sole maize(SM), sole peanut(SP), and an intercrop consisting of four rows of maize and six rows of peanut(IM and IP). The results showed that the intercropping system had yield advantages based on the land equivalent ratio(LER) values of 1.15 and 1.16 in the two years, respectively. Averaged over the two years, the yield of maize in the intercropping was increased by 61.05% compared to that in SM, while the pod yield of peanut was decreased by 31.80% compared to SP. Maize was the superior competitor when intercropped with peanut, and its productivity dominated the yield of the intercropping system in our study. The increased yield was due to a higher kernel number per ear(KNE). Intercropping increased the light transmission ratio(LTR) of the ear layer in the maize canopy, the active photosynthetic duration(APD), and the harvest index(HI) compared to SM. In addition, intercropping promoted the ratio of dry matter accumulation after silking and the distribution of ~(13) C-photosynthates to grain compared to SM. In conclusion, maize/peanut intercropping demonstrated the potential to improve the light condition of maize, achieving enhanced photosynthetic characteristics that improved female spike differentiation, reduced barrenness, and increased KNE. Moreover, dry matter accumulation and ~(13) C-photosynthates distribution to grain of intercropped maize were improved, and a higher grain yield was ultimately obtained.     

宁夏中部生态移民区土地利用时空变化分析

通过解译宁夏中部红寺堡区1989年、1999年、2006年、2012年TM遥感影像,获取该区域生态移民前后4期土地利用数据,对1989~2012年以来土地利用变化情况进行了分析。结果表明,各个时间段的土地利用变化差异性显著。1989~1999年,由于大规模的土地开荒和红寺堡灌区的建设,耕地面积持续增加,同时该区域开始有了水浇地,而林草面积相应减少;1999~2006年,由于退耕还林还草政策的实施,耕地中的旱地被逐渐退耕为草地或发展为水浇地,林草面积开始由减少转为增加,区域土地利用开始合理化;2006~2012年,随着生态移民工程和生态建设工程的成熟发展,林草覆盖面积进一步增加,水浇地面积继续稳步增加,而未利用地和旱地面积持续下降。研究结果为区域土地资源的合理利用及生态移民工程的进一步顺利开展提供可靠依据。