Cropland physical disturbance intensity： plot-scale measurement and its application for soil erosion reduction in mountainous areas

Various kinds of human disturbances on cropland are the main reasons for soil erosion and land degradation.Farming practices in mountainous areas vary greatly among cropland plots because of the heterogeneity of biophysical conditions and differences in farmers'management behavior.The main purpose of this paper is to develop a composite index of cropland physical disturbance intensity(CLDI)to reflect the plot-scale discrepancy of potential soil erosion in mountainous areas.The study was based on both plot survey and household interview data,collected from six typical catchments in mountainous areas of southwestern China.Four kinds of physical disturbance practices and two kinds of conservation practices during one crop rotation period were synthesized to develop the CLDI index.The rough set theory was referenced to avoid subjectivity during weight allocation.The results show that conventional tillage,deep fertilization,and manual weeding are the main causes of cropland soil erosion,whereas manure application in combination with seasonal fallow reduces soil erosion.Different crop types as well as cropland location factors determine the spatial pattern of CLDI.Crop rotation modes with major crops of tobacco and maize resulted in a maximal CLDI,and cropland plots with a distance radius of 150 meters away from households received the most intensive physical disturbance.These results are critical to help better protect rural environments in mountainous areas.Based on the results,methods to reduce cropland soil erosion are suggested.

Biotechnological Strategies for Phytoremediating Triazinic Herbicides in the Humid Pampa （Argentine）

In agricultural producer countries, the use of chlorinated herbicides （atrazine）, associated to intensive farming practices, overflows the ecosystems natural attenuation capacity. Thus, herbicide residues contaminate the soils and water sources, increasing the risk for human health and wildlife. Humid Pampa is the main agricultural region in one of the world＇s largest herbicide consumer countries; hence, technologies to remediate its residues are needed. In this context, phytoremediation is an effective, environmental friendly and publicly accepted option. Accordingly, the objective of designing biotechnological strategies for phytoremediating triazinic herbicide residues in an integrated approach to the ongoing Humid Pampa agricultural trend is raised. In this way, strategies according to the edaphic, topogeographic and fanning practices characteristics of this region where established. In those strategies, the adequate selection of plant species is essential. For that purpose, atrazine tolerance assays were performed in simple （semisolid agar medium） and complex （microcosms） experimental systems implanted with Lolium multiflorum, Lotus sp. and Quenopodium quinoa. L. multiflorum was selected and evaluated via atrazine dissipation assays with soil. Atrazine soil content was determined by solvent extraction and subsequent HPLC-UV analysis, observing statistically significant attenuation levels at 21 days. According to the observed results, a strategy for scaling up the application to field conditions is proposed.