Trophic niche but not abundance of Collembola and Oribatida changes with drought and farming system

Higher frequencies of summer droughts are predicted to change soil conditions in the future affecting soil fauna communities and their biotic interactions. In agroecosystems drought effects on soil biota may be modulated by different management practices that alter the availability of different food resources. Recent studies on the effect of drought on soil microarthropods focused on measures of abundance and diversity. We here additionally investigated shifts in trophic niches of Collembola and Oribatida as indicated by stable isotope analysis (13C and 15N). We simulated short-term summer drought by excluding 65% of the ambient precipitation in conventionally and organically managed winter wheat fields on the DOK trial in Switzerland. Stable isotope values suggest that plant litter and root exudates were the most important resources for Collembola (Isotoma caerulea, Isotomurus maculatus and Orchesella villosa) and older plant material and microorganisms for Oribatida (Scheloribates laevigatus and Tectocepheus sarekensis). Drought treatment and farming systems did not affect abundances of the studied species. However, isotope values of some species increased in organically managed fields indicating a higher proportion of microorganisms in their diet. Trophic niche size, a measure of both isotope values combined, decreased with drought and under organic farming in some species presumably due to favored use of plants as basal resource instead of algae and microorganisms. Overall, our results suggest that the flexible usage of resources may buffer effects of drought and management practices on the abundance of microarthropods in agricultural systems.

Copper use in organic agriculture in twelve European countries.

Reduction of copper-based fungicides with the final aim of phasing out has a high priority in European policy as well as in organic agriculture. Our survey aims at providing an overview of the current use of copper-based plant protection products in European organic agriculture and the need for alternatives to allow policy makers to develop strategies for a complete phasing out. Due to a lack of centralized databases on pesticide use, our survey combines expert knowledge on permitted and real copper use per crop and country with statistics on organic area. In the 12 surveyed countries, covering together 83% of the European organically managed horticultural area, we calculated approximately 3258 t copper metal per year are consumed by organic agriculture, equalling to 53% of the permitted annual dosage. This amount is split between olives (1263 t y-1, 39%), grapevine (990t y-1, 30%), and almonds (317 t y-1, 10%), followed by other crops with much smaller annual uses (<80 t y-1). Potato, usually considered a highly demanding plant for copper inputs, only uses 39 t y-1 of copper per year. In 56% of the allowed cases (countries × crops), farmers use less than half of the allowed amount, and in 27% less than a quarter, with some variability between countries. Considering the large volumes of copper used annually, replacement of copper seems only feasible if all preventive strategies from the crop protection pyramid are fully implemented and several affordable alternative plant protection products are successfully brought to the market.

Effects on Crop Development, Yields and Chemical Composition of Celeriac (Apium graveolens L. var. rapaceum) Cultivated Underneath an Agrivoltaic System

Agrivoltaic (AV) systems increase land productivity through the combined production of renewable energy and food. Although several studies have addressed their impact on crop production, many aspects remain unexplored. The objective of this study was to determine the effects of AV on the cultivation of celeriac, a common root vegetable in Central Europe. Celeriac was cultivated in 2017 and 2018 as part of an organically managed on-farm experiment, both underneath an AV system and in full-sun conditions. Under AV, photosynthetic active radiation was reduced by about 30%. Monitoring of crop development showed that in both years, plant height increased significantly under AV. Fresh bulb yield decreased by about 19% in 2017 and increased by about 12% in 2018 in AV, but the changes were not significant. Aboveground biomass increased in both years under AV, but only increased significantly in 2018. As aboveground biomass is a determinant of root biomass at harvest in root vegetables, bulb yields may be further increased by a prolonged vegetation period under AV. Compound analysis of celeriac bulbs did not show any clear effects from treatment. As harvestable yields were not significantly reduced, we concluded that celeriac can be considered a suitable crop for cultivation under AV.

EFFECTS OF CULTIVATION SYSTEMS AND CULTIVARS ON GROWTH AND YIELD PERFORMANCE OF JAPANESE EGGPLANT IN THAILAND

In the current study impacts of different cultivation systems and Japanese eggplant cultivars on their growth and yield were determined. Four Japanese eggplant cultivars viz., ‘Fullness’, ‘Black Beauty’, ‘Wasedaimaru’ and ‘Israel’ were grown under two systems of organic and conventional cultivations from 2 April to 16 July 2018 at the Faculty of Agricultural Technology, Songkhla Rajabhat University, Muang, Songkhla. The experimental arrangement used in this study was split-plots design (SPD) within a randomized complete block design (RCBD) with four replications. Results of the study indicated that ‘Wasedaimaru’ and ‘Fullness’ were suitable for growing under the organically managed production. ‘Wasedaimaru’ grown under an organic cultivation system had a lower yield per plant at 4,444.00g than grown under conventional chemical cultivation at 6,848.40g. The organic yield was not significantly different (p≤0.05) from ‘Fullness’ grown under organic cultivation at 3,947.40g. ‘Wasedaimaru’ and ‘Fullness’ were identified as suitable cultivars for production under organic cultivation in Thailand with high yield.

Nitrous Oxide Emission from Grazing Is Low across a Gradient of Plant Functional Diversity and Soil Conditions

Nitrous oxide (N2O) emissions from pastures can vary significantly depending on soil and environmental conditions, nitrogen (N) input, as well as the plant’s ability to take up the N. We tested the hypothesis that legume-based N sources are characterized by significantly lower emission factors than mineral N based dairy systems. Therefore, this study monitored N2O emissions for a minimum of 100 days and up to two growing seasons across a gradient of plant species diversity. Emissions were measured from both grazed pastures and a controlled application of urine and dung using the static chamber method. About 90% of the simulated experiments’ accumulated N2O emissions occurred during the first 60–75 days. The average accumulated N2O emissions were 0.11, 0.87, 0.99, and 0.21 kg ha−1 for control, dung, urine patches, and grazed pastures, respectively. The N uptake efficiency at the excreta patch scale was about 70% for both dung and urine. The highest N2O-N emission factor was less than half compared with the IPCC default (0.3 vs. 0.77), suggesting an overestimation of N2O-N emissions from organically managed pastures in temperate climates. Plant diversity showed no significant effect on N2O emission. However, functional groups were significant (p < 0.05). We concluded that legume-containing pasture systems without a fertilizer addition generally appear capable of utilizing nitrogen inputs from excreta patches efficiently, resulting in low N2O emissions.

Evaluation of Cultivars and Spray Programs for Organic Grape Production in Virginia

The French American hybrid grape cultivars Corot noir and Arandell (Vitis sp.), and Vidal blanc and Petit Manseng (Vitis vinifera), along with different spray programs, were evaluated for potential organic production in Virginia from 2013 to 2014. Results obtained in the study demonstrate that organic wine grape production in Virginia can be achieved by using select grape cultivars and spray programs. With the exception of Vidal blanc, disease severity and disease incidence were below the threshold for maintaining healthy vines in all organically managed grape cultivars. ‘Vidal blanc’ was not sufficiently resistant to downy mildew (Plasmopara viticola), precluding it from potential organic management in Virginia. The study also demonstrated significant disease resistance in Virginia of the cultivar Arandell, released by Cornell University (Ithaca, NY) in 2013. The results suggest that the organically registered fungicide Bacillus subtilis is effective in reducing the severity and incidence of black rot (Guignardia bidwellii) and phomopsis cane and leaf spot (Phomopsis viticola). The chemistry of organically managed berries harvested in 2014 met minimum requirements for wine production with soluble solids, titratable acidity, and pH ranging from 18.7% to 20.2%, 7.6 to 8.0 g·L−1, and 3.3 to 3.4, respectively, in ‘Arandell’ and ‘Corot noir’; and 21.0% to 24.4%, 7.8 to 9.6 g·L−1, and 2.7 to 2.9, respectively, in ‘Petit Manseng’ and ‘Vidal blanc’ juice.

Weed Suppression Potential of Living Mulches, Newspaper Hydromulches, and Compost Blankets in Organically Managed Carrot Production

Direct seeding into strip-tilled zones (STZs) of living mulches may require weed suppression tactics for soil surfaces exposed within the STZ. Three surface mulch options (hydromulch, compost blanket, and a no-mulch control) were evaluated for their ability to suppress weeds and improve crop performance when applied in STZs seeded to carrot (Daucus carota). These STZs were located within one of five living mulch options [red clover (Trifolium pratense), white clover (Trifolium repens), perennial ryegrass (Lolium perenne), a weed-free control, and a weedy control]. From measurements spanning 2 years at two North Dakota locations, dry weed biomass was lower in STZs where hydromulch or compost blankets were applied compared with the no-mulch control (12, 13, and 82 g·m−2, respectively). The presence of a living mulch adjacent to the STZ reduced carrot root biomass by 49% to 84% compared with the weed-free control. Further research should 1) investigate methods for reducing yield loss from living mulches, and 2) develop biodegradable alternatives to plastic mulches.