Transformation toward agricultural sustainability in New Zealand hill country pastoral landscapes

A multi-stakeholder representative group was established to oversee a project examining the economic and environmental performance of a representative North Island hill country catchment farm at Whatawhata in the western Waikato region of New Zealand. The group included representation from landowners, government agencies and scientists. The group was facilitated through an action research approach incorporating three phases: (1) awareness; (2) forecasting; and (3) implementation. The group identified a set of goals and indicators relevant to achieving a “well managed rural hill catchment” The indicators were used to (a) assess the current state of the catchment farm in relation to the goals; (b) evaluate a range of strategies for improving system performance and (c) evaluate progress toward the goals following land use changes implemented within the catchment farm. Key issues for the group included the availability of data and the setting of appropriate performance benchmarks. From both economic and environmental points of view, the existing farm system was failing to meet the goals set by the management group. Key factors driving these outcomes included the physical and productivity limitations of the soil resource, poor livestock performance and poor water quality. A mixture of research observations, decision support models and expert stakeholder knowledge indicated scope for improving performance through forestry, riparian management, erosion control and livestock intensification options. Based on their evaluation of the forecasting results, the group developed a new land use plan, which depended on significant capital investment in land use and enterprise change. Subsequent monitoring of soils, vegetation, water quality, animal production and financial results over four years showed marked improvement in a number of key performance indicators. In particular, sediment and phosphorus loads and faecal coliform levels decreased rapidly, native forest fragments showed early signs of restoration, lamb and beef productivity increased and the per hectare financial returns of the pastoral component increased. Better matching of land use to land capability has led to short-term improvement in some aspects of the economic and environmental performance of the catchment farm. Progress toward a more sustainable agricultural system was achieved, but at a substantial cost for transformation of the biophysical system, which has implications for the wider sector.     

Modeling soil carbon sequestration in agricultural lands of Mali

Agriculture in sub-Saharan Africa is a low-input low-output system primarily for subsistence. Some of these areas are becoming less able to feed the people because of land degradation and erosion. The aim of this study is to characterize the potential for increasing levels of soil carbon for improving soil quality and carbon sequestration. A combination of high- and low-resolution imagery was used to develop a land use classification for an area of 64 km² near Omarobougou, Mali. Field sizes were generally small (10–50 ha), and the primary cultivation systems are conventional tillage and ridge tillage, where tillage is performed by a combination of hand tools and animal-drawn plows. Based on land use classification, climate variables, soil texture, in situ soil carbon concentrations, and crop growth characteristics, the EPIC-Century model was used to project the amounts of soil carbon sequestered for the region. Under the usual management practices in Mali, mean crop yield reported (1985–2000) for maize is 1.53 T ha⁻¹, cotton is 1.2 T ha⁻¹, millet is 0.95 T ha⁻¹, and for sorghum is 0.95 T ha⁻¹. Year-to-year variations can be attributed to primarily rainfall, the amount of plant available water, and the amount of fertilizer applied. Under continuous conventional cultivation, with minimal fertilization and no residue management, the soil top layer was continuously lost due to erosion, losing between 1.1 and 1.7 Mg C ha⁻¹ over 25 years. The model projections suggest that soil erosion is controlled and that soil carbon sequestration is enhanced with a ridge tillage system, because of increased water infiltration. The combination of modeling with the land use classification was used to calculate that about 54 kg C ha⁻¹ year⁻¹ may be sequestered for the study area with ridge tillage, increased application of fertilizers, and residue management. This is about one-third the proposed rate used in large-scale estimates of carbon sequestration potential in West Africa, because of the mixture of land use practices.     

冀北山区农业生态效率时空演变特征及预测分析

基于2008—2018年冀北山区21个县域的面板数据构建评价指标体系,采用超效率SBM模型对冀北山区农业生态效率进行测度分析;通过Kernel密度估计的时序分析和ArcGIS的方向分布探究农业生态效率时空分布格局和宏观演变特征;构建传统与空间马尔科夫转移概率矩阵,进一步探究冀北山区农业生态效率时空演变的内在规律,并预测长期演变趋势。2008—2018年冀北山区农业生态效率整体呈现波动中上升的趋势,大多数县域达到相对有效,县域间农业生态效率差距缩小,农业生态效率重心向东北方向偏移3.95 km;冀北山区农业生态效率受地理邻域背景影响作用较为显著,空间溢出效果明显,具有维持原状态的稳定性,相邻年份间难以实现大幅度跨越式转移,同时,冀北山区农业生态效率向中高等级转移聚集的趋势明显,具有一定的提升潜力,但难以实现整体向高等级的转移。研究农业生态效率的时空演变特征及发展趋势,定量化反映区域农业的可持续发展水平,可为当地政策的制定提供一定的参考.     

A tool for community-based assessment of the implications of development on water security in hillside watersheds

Development and population growth in Latin American countries with steep slope farming are likely to further increase pressures on water and land resources. A methodology was developed for assessing water availability and use under different development pathways at a watershed scale to determine whether water security is a potential problem, and if so, under what conditions it is likely to occur. This methodology makes use of a GIS-based spatial water budget model for simulating stream water availability, water use and stream flow control on a daily basis at a watershed scale. Here, we analysed water availability under three plausible development scenarios for the 3246 ha Cabuyal River watershed in southwest Colombia in the year 2025: Corporate Farming (CF), Ecological Watershed (EW), and Business as Usual (BU). Simulated average river flows at the watershed outlet were, respectively, 874, 796 and 925 l s⁻¹ for the CF, EW and BU scenarios. The contribution of base flow to river flow (base flow index) was on average, 80.8, 85.6 and 77.9%, respectively, for the three scenarios. The watershed had the potential to meet the anticipated increase in water use under each explorative scenario. However, dams were necessary to store irrigation water in the CF scenario, otherwise over 60% of the available water would have been used during the dry season. Such a high figure raises concerns about effects on aquatic and riparian ecology, concentrations of potential contaminants, water reserves for especially low rainfall years, and the watershed resilience to meet temporarily higher water needs during the day. Analyses indicated that current water-use conflicts in the watershed can be resolved if irrigation water supply is separated from drinking water supply. This study helped reduce some of the complexity associated with the interdependencies between land and water resources, the impact of using them, and spatial linkages within the watershed. Results of this study can be used for teaching local stakeholders about basic landscape responses and helping multi-institutional alliances to become proactive and to guide development to the benefit of local communities.     

基于LU-SWAT模型的土地利用/覆被变化对水文过程的影响研究——以黑河上游为例

【目的】揭示内陆河流域集水区土地利用/覆被变化对水文过程的影响及其成因。【方法】基于能够逐年调用土地利用/覆被数据的LU-SWAT模型,并结合控制变量法研究了黑河流域集水区黑河上游1990—2009年土地利用/覆被变化对地表径流、侧向流、蒸散发量、地下径流以及总产水量的影响。【结果】LU-SWAT模型对于黑河上游月、年出山径流模拟结果较好,其月径流模拟的纳什系数为0.93,相关性系数为0.94;其年径流模拟的纳什系数为0.83,相关性系数为0.86。此外,其对各个水文要素的模拟结果符合西北干旱区内陆河流域集水区的水文特征;1990—2001年黑河上游土地利用变化主要表现在林地的减少,而2002—2009年土地利用的变化除了林地和草地的增加之外,还表现在裸地的大面积减少;1990—2001年黑河上游地表径流、侧向流、蒸散发量以及总产水量都呈现增加趋势,而地下径流呈减少趋势,2002—2009年流域地表径流、侧向流、蒸散发量以及总产水量减少,而地下径流量增加。在黑河上游,干旱条件下各水文要素对于土地利用覆被变化的响应更明显。【结论】1990—2001年林地的减少可能是流域地表径流、侧向流、蒸散发量以及总产水量都呈现增加趋势而地下径流呈减少趋势的主要原因。2002—2009年裸地的大面积减少可能是流域地表径流、侧向流、蒸散发量以及总产水量减少而地下径流量增加的主要原因。