Purpose: Rain storm events mobilise large proportions of fine sediments in catchment systems. 28 Sediment from agricultural catchments are often adsorbed by nutrients, heavy metals and other 29 (in)organic pollutants that may impact downstream environments. To mitigate erosion, 30 sediment transport and associated pollutant transport it is crucial to know the origin of the 31 sediment that is found in the drainage system and, therefore, it is important to understand 32 catchment sediment dynamics throughout the continuity of runoff events. 33 Materials and methods: To assess the impact of the state of a catchment on the transport of 34 fine suspended sediment to catchment outlets an algorithm has been developed which classifies 35 rain storm events into simple (clockwise, counterclockwise) and compound (figure-of-eight; 36 complex) events. This algorithm is the first tool that uses all available discharge and suspended 37 sediment data and analyses these data automatically. A total of 797 runoff events from three 38 experimental watersheds in Navarre (Spain) were analysed with the help of long-term, high 39 resolution discharge and sediment data that was collected between 2000-2014. 40 Results and discussion: Morphological complexity and in-stream vegetation structures acted 41 as disconnecting landscape features which caused storage of sediment along the transport 42 cascade. The occurrence of sediment storage along transport paths was therefore responsible 43 for clockwise hysteresis due to the availability of in-stream sediment which could cause the 44 "first flush" affect. Conversely, the catchment with steeper channel gradients and a lower 45 stream density showed much more counterclockwise hysteresis due to better downstream and 46 lateral surface hydrological connectivity. In this research hydrological connectivity is defines 47 as the actual and potential transfer paths in a catchment. The classification of event SSC-Q 48 hysteresis provided a seasonal benchmark value to which catchment managers can compare 49 runoff events in order to understand the origin and locations of suspended sediment in the 50 3 catchment. 51 Conclusions: A new algorithm uses all available discharge and suspended sediment data to 52 assess catchment sediment dynamics. From these analysis, the catchment connectivity can be 53 assessed which is useful to develop catchment land management.
Core Ideas Stock unearthing method assumes that soil surface is planar between vines.Improved stock unearthing method enhances the survey due to extra measurements.Indispensable to consider the timing of the measures in relation to tillage events.Stock unearthing method underestimates soil erosion rates by –14.2% in 1‐d plowed vineyards.Stock unearthing method underestimates erosion rates by –37.8% in 86‐d plowed vineyards. Vineyards have proven to be one of the most degraded agricultural ecosystems due to very high erosion rates, which are typically measured at fine temporal and spatial scales. Long‐term soil erosion measures are rare, but this information may be indispensable for a proper understanding of the vineyard soil system, landscape evolution, and crop production. The stock unearthing method (SUM) is a common topographical measurement technique developed to assess long‐term erosion rates. The reliance of the SUM has been questioned and should be replaced by an improved measurement technique. In this paper, we demonstrate the added value (improved accurate, low cost, and faster than photogrammetrically methods) of the improved stock unearthing method (ISUM). It was shown that large errors may have been made in previous assessments of soil erosion on vineyards, as the old method did not make measurements in the inter‐row area or consider the timing of the erosion assessment in relation to tillage events. We found that this caused the SUM to severely underestimate soil erosion rates by –14.2 and –37.8% in 1‐ and 86‐d tillage vineyards in one location, respectively. Furthermore, the increased measurement resolution attained from the ISUM allowed for the detailed assessment of micro‐topographical change. Soil loss maps were able to detect the locational changes in soil depletion and accumulation, as well as continuous soil movement features in the inter‐row areas. Ultimately, this leads to a more accurate estimate of the actual soil erosion rates in vineyards.
A thorough understanding of commonly used herbicide application practices and technologies is needed to provide recommendations and determine necessary application education efforts. An online survey to assess ground and aerial herbicide application practices in Arkansas was made available online in spring 2019. The survey was direct-emailed to 272 agricultural aviators and 831 certified commercial pesticide applicators, as well as made publicly available online through multiple media sources. A total of 124 responses were received, of which 75 responses were specific to herbicide applications in Arkansas agronomic crops, accounting for approximately 49% of Arkansas’ planted agronomic crop hectares in 2019. Ground and aerial application equipment were used for 49 and 51% of the herbicide applications on reported hectares, respectively. Rate controllers were commonly used application technologies for both ground and aerial application equipment. In contrast, global positioning system-driven automatic nozzle and boom shut-offs were much more common on ground spray equipment than aerial equipment. Applicator knowledge of nozzles and usage was limited, regardless of ground or aerial applicators, as only 28% of respondents provided a specific nozzle type used, indicating a need for educational efforts on nozzles and their importance in herbicide applications. Of the reported nozzle types, venturi nozzles and straight stream nozzles were the most commonly used for ground and aerial spray equipment, respectively. Spray carrier volumes of 96.3 and 118.8 L ha-1 for ground spray equipment and 49.6 and 59.9 L ha-1 for aerial application equipment were the means of reported spray volumes for systemic and contact herbicides, respectively. Respondents indicated application optimization was a major benefit of utilizing newer application technologies, herbicide drift was a primary challenge, and expressed research needs included adjuvants, spray volume efficacy, and herbicide drift. Findings from this survey provided insight into current practices, technologies, and needs of Arkansas herbicide applicators. Research and education efforts can be implemented as a result to address aforementioned needs while providing applied research-based information to applicators based on current practices.
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