Endogenous technological change and pollution abatement

Nonpoint source pollution control is a more complicated process than traditional analysis suggests. Whether a new pollution abatement technology is developed exogenously or endogenously and the per unit reduction in the rate at which a pollutant associated with the use of a factor of production needed to produce an agricultural commodity due to this technology enters the environment are critical factors in the determination of the effects of agricultural production on the pollutant stock. These are the issues addressed here. The optimal current period research and development expenditures on an endogenously induced abatement technology associated with the use of a factor of production giving rise to environmental externalities are shown to be a function of, among other things, the cumulation of all research and development expenditures, the probability of an abatement technology being developed, the level of use of the factor of production, the unit pollution tax on the factor, the rate of time preference (discount rate), the rate at which the pollutant associated with the factor enters the environment, the rate of discharge of the pollutant stock, and so forth. Finally, the analysis demonstrates that a reduction in pollution by the adoption of an abatement technology may lead to an increase in the pollutant stock as a result of endogenous technological change associated with the pollution abatement. When the rate of pollution reduction is greater than a threshold, however, the adoption of an endogenously determined abatement technology will unequivocally lead to a reduction in the pollutant stock.The views expressed are those of the authors and do not necessarily represent the policies of the US Department of Agriculture or the views of other US Department of Agriculture staff members.     

黄淮海平原农业综合开发的效益和粮食增产潜力

黄淮海平原经过1988-1993年农业综合开发,取得了明显的经济、生态和社会效益。改造中低产田409万ha,开发区粮食年平均增长率达4.0%,其增产量占全区增产总量的42.5%,农业开发的贡献几乎与传统农业的贡献相等。预测1995-2000年,即使是农业综合开发的规模与前六年相同,但是,由于水利工程效益更充分地发挥和农业的科技含量持续增长,开发区粮食完全可能增产达90亿kg.     

Sustainable or Not? Tourism Development in Agricultural Heritage Sites

Tourism is often considered as one of the dynamic conservation and adaptive management approaches in Agricultural Heritage Sites. It has been over 15 years since the GIAHS programme was initiated in China, and tourism developed quickly in the Agricultural Heritage Sites, to some extent because many researchers consider tourism as a significant engine of the local economy. However, this is contrary to the original intention of agricultural heritage tourism as it was proposed in the first place. Apparently, there are some overt problems during the tourism development process, which are mainly as follows: Some threats to Agricultural Heritage Systems are ubiquitous; The tourism development mode in Agricultural Heritage Sites is questionable; Community involvement is difficult to implement; And the negative environmental impacts are easy to overlook. Under the context of global development, the UNWTO sustainable tourism criteria provide some guidance for agricultural heritage tourism. Based on the Global Sustainable Tourism Criteria, combined with previous survey experiences and related researches, this paper analyzes the tourism sustainability of all the 15 GIAHS sites in China, and explores the current sustainable tourism development level. On this basis, an agricultural heritage sustainable tourism development framework was built in an attempt to find the road to sustainability for agricultural heritage tourism. The framework in the global and local contexts is trying to connect all the important elements related to agricultural heritage tourism according to the UNWTO sustainable tourism criteria.     

The Evaluation of Food and Livelihood Security in a Globally Important Agricultural Heritage Systems (GIAHS) Site

Based on the basic selection criteria of Globally Important Agricultural Heritage Systems (GIAHS) and food and livelihood security research trends, this paper established an evaluation framework and indicator system for food and livelihood security in GIAHS and selected the first GIAHS site in the Qinghai-Tibet Plateau as a case for empirical evaluation. The results demonstrate that the food and livelihood security of farmers at this site was at a medium level, with an average evaluation value of 2.91, which still lagged behind the level of better food and livelihood security. Specifically, the average values of farmers’ evaluation of food security and livelihood security were 1.43 and 1.48, respectively, which show that farmers’ food security in the study area was at a medium level and that of livelihood security was relatively good. Simultaneously, the more simple a farmers’ economic activities (i.e., agriculture-oriented economic activities or non-agriculture-oriented economic activities), the worse their food and livelihood security; while the more diversified the economic activities (i.e., engaged in part-time economic activities), the better the food and livelihood security.     

The Significance of Traditional Culture for Agricultural Biodiversity—Experiences from GIAHS

Agricultural biodiversity has a high importance in social-cultural, economic, and environmental aspects, and can help in adapting to and withstanding climate change. Conserving the GIAHS sites and the important components within them can help conserve the agricultural biodiversity and traditional agricultural culture of the whole country. This study considered Ifugao Rice Terraces, Dong’s Rice-Fish-Duck System, and Hani Rice Terraces System as three examples which show that traditional culture can be used to protect agricultural biodiversity, while as a carrier of traditional culture, agricultural biodiversity also conveys and protects the traditional culture of the nation. According to the analyses, through several years of efforts, the status of agricultural biodiversity and traditional culture in them has improved. Then, to further promote agricultural biodiversity conservation and traditional culture protection, several suggestions are made, such as establishing community seed banks; documenting and preserving traditional farming methods, techniques, and tools and developing participatory activities which encourage more farmers to participate in the protection work.     

Suppressive Effects of Traditional Mulching Using Japanese Knotweed (Fallopia japonica) on Solanaceae Crop Diseases

Poaceae plant species, such as silver grass, are commonly used in mulching activities Japan. In contrast, local farmers have traditionally used Japanese knotweed (Fallopia japonica) mulch in the cultivation of solanaceous crops in the Nishi-Awa area of Japan, which is a Globally Important Agricultural Heritage Systems site. We have previously evaluated the positive effects of Japanese knotweed mulching on solanaceous crops, such as eggplants, tomato, and potato. In the present study, we observed that the naturally occurring diseases in the solanaceous crops tended to decrease when the knotweed mulching system was adopted, in comparison to when Poaceae mulch was adopted. In eggplants, leaf mold and powdery mildew decreased under Japanese knotweed mulching. We further evaluated the effects of Japanese knotweed mulching by inoculating test plants with Pseudomonas cichorii. We observed suppression of bacterial disease and tomato mosaic virus under Japanese knotweed mulching and following spraying with Japanese knotweed extracts. In addition, disease-resistance genes were expressed at high levels in Arabidopsis thaliana, a model plant, following treatment with Japanese knotweed extracts. The results suggest that Japanese knotweed has potential applications in future sustainable agriculture activities.     

基于MODIS和TRMM数据的黄土高原农业干旱监测

农业干旱对农业生产影响最为严重,基于站点观测数据的干旱指数不能准确监测区域尺度的农业干旱特征。因此,利用2003—2015年MODIS地表温度(LST)、植被指数(NDVI)和TRMM降水(3B43)数据以及1960—2015年黄土高原地区及周边92个气象站点的月均温和月降水量数据,构建了综合遥感干旱监测模型规模干旱条件指数(Scale Drought Condition Index,SDCI),对黄土高原地区农用地生长季(4～10月)旱情的时空分布特征进行研究,结果表明:黄土高原地区农用地生长季多年平均干旱状态为中度干旱,干旱程度在空间上表现为西北部较严重,东南部较轻。2003—2015年黄土高原地区旱情年际变化总体呈波动减轻趋势,2003—2007年旱情越来越严重,2007—2014年旱情波动减轻,2014—2015年旱情有所加重。黄土高原地区旱情年内变化表现4～8月持续减轻,8～10月持续加重,干旱程度具体表现为4月、5月、6月和10月呈中度干旱,7月、8月和9月呈轻度干旱。研究表明利用多源遥感数据构建的具有适当权重的SDCI可以有效监测黄土高原地区作物生长季的干旱状况。     

The Effect of Farmland Fragmentation on the Intensity of Farmland in Different Utilization Ways

The agricultural development of mountainous areas in China is undergoing the transformation from the traditional agricultural land use mode dominated by single and inefficient grain production to the new agricultural land use mode such as high-yield and efficient horticultural crops. The research on the impact of farmland fragmentation on the agricultural land intensity degree is the basis of agricultural modernization and land remediation in mountainous areas. Based on the UAV high-resolution remote sensing image data of two typical villages in Guizhou Province and the questionnaire survey data of farmers, using the road accessibility index of farmers' plot, the area index and the shape index to measure the degree of farmland fragmentation, we analyzed the impact of different degrees of farmland fragmentation on the traditional and new types of farmland use intensification. The research showed that the farmland fragmentation had a significant negative impact on the intensive degree of agricultural land, but the impact on the intensive degree of agricultural land in different ways of use was different. With the intensification of the degree of farmland fragmentation, the impact on the input and output of horticultural crops and other new-type agricultural land utilization was less than that of grain crops and other traditional agricultural land utilization. Adjusting agricultural structure and transformation of farmland utilization greatly alleviated the negative impact of farmland fragmentation on farmland intensity in mountainous areas.     

Assessing the optimal preprocessing steps of MODIS time series to map cropping systems in Mato Grosso,Brazil

The adoption of new cropping practices such as integrated Crop-Livestock systems (iCL) aims at improving the land use sustainability of the agricultural sector in the Brazilian Amazon. The emergence of such integrated systems, based on crop and pasture rotations over and within years, challenges the remote sensing community who needs to implement accurate and efficient methods to process satellite image time series (SITS) in order to come up with a monitoring protocol. These methods generally include a SITS preprocessing step which can be time consuming. The aim of this study is to assess the importance of preprocessing operations such as temporal smoothing and computation of phenological metrics on the mapping of main cropping systems (i.e. pasture, single cropping, double cropping and iCL), with a special emphasis on the iCL class. The study area is located in the state of Mato Grosso, an important producer of agriculture commodities located in the Southern Brazilian Amazon. SITS were composed of a set of 16-day composites of MODIS Vegetation Indices (MOD13Q1 product) covering a one year period between 2014 and 2015. Two widely used classifiers, i.e. Random Forest (RF) and Support Vector Machine (SVM), were tested using five data sets issued from a same SITS but with different preprocessing levels: (i) raw NDVI; (ii) raw NDVI + raw EVI; (iii) smoothed NDVI; (iv) NDVI-derived phenometrics; (v) raw NDVI + phenometrics. Both RF and SVM classification results showed that the “raw NDVI + raw EVI” data set achieved the highest performance (RF OA = 0.96, RF Kappa = 0.94, SVM OA = 0.95, SVM Kappa = 0.93), followed closely by the “raw NDVI” and the “raw NDVI + phenometrics” datasets. The “NDVI-derived phenometrics” alone achieved the lowest accuracies (RF OA = 0.58 and SVM OA = 0.66). Considering that the implementation of preprocessing steps is computationally expensive and does not provide significant gains in terms of classification accuracy, we recommend to use raw vegetation indices for mapping cropping practices in Mato Grosso, including the integrated Crop-Livestock systems.     

农业地理学发展述要

本文以动态观点,提纲挈领地论述我国以及西欧、北美和苏联等主要国家近代农业地理学的发展过程。主要的传统研究是以地域为单元来探讨农业生态、土地利用、粮食生产与供应,农业地域类型和农业区划,编写区域农业地理志和农业图集等。作者认为农业地理学是典型的边缘科学,它是农业科学又是地理科学的组成部分。它的主要研究对象是农业经济活动的地域系统,它的形成过程,结构特征和发展规律。根据我国现代化建设的要求,在90年代我国农业地理学将着重研究:农业发展的资源基础,人口与粮食平衡,农业生产和劳动力的结构变化,农村工业化和贫困山区脱贫致富问题。