Agriculture, Volume 6, Issue 1 (March 2016) – 10 articles

A laboratory study was conducted to test the effects of biochars made from different feedstocks on soil quality indicators of arid soils. Biochars were produced from four locally-available agricultural residues: pecan shells, pecan orchard prunings, cotton gin trash, and yard waste, using a lab-scale pyrolyzer operated at 450 °C under a nitrogen environment and slow pyrolysis conditions. Two local arid soils used for crop production, a sandy loam and a clay loam, were amended with these biochars at a rate of 45 Mg·ha⁻¹ and incubated for three weeks in a growth chamber. The soils were analyzed for multiple soil quality indicators including soil organic matter content, pH, electrical conductivity (EC), and available nutrients. Results showed that amendment with cotton gin trash biochar has the greatest impact on both soils, significantly increasing SOM and plant nutrient (P, K, Ca, Mn) contents, as well as increasing the electrical conductivity, which creates concerns about soil salinity. Other biochar treatments significantly elevated soil salinity in clay loam soil, except for pecan shell biochar amended soil, which was not statistically different in EC from the control treatment. Generally, the effects of the biochar amendments were minimal for many soil measurements and varied with soil texture. Effects of biochars on soil salinity and pH/nutrient availability will be important considerations for research on biochar application to arid soils. Full article

We used macro-economic data and aggregated waste data to estimate that, in 2011, New Zealand households generated over 224,000 tonnes of food waste, and New Zealand industry generated over 103,000 tonnes of food waste. We split New Zealand’s food waste into 14 food-waste categories and found that 7% is related to “fresh” produce, and 93% “processed” food waste. The value of New Zealand’s food waste in 2011 is estimated to be NZ $568 million, or $131 per person. Furthermore, New Zealand’s food waste represents 163 × 10⁹ calories in total, and avoidable food waste would be able to feed between 50,000 and 80,000 people a year. New Zealand food waste embodies 4.2 × 10⁶ tonnes of CO₂-e, 4.7 × 10⁹ m³ of water, and 29 × 10³ TJ of energy. Nonetheless, we find that, compared to other nations, New Zealanders waste less food per capita by weight, value and calorie. Full article

This study analyzes soil sealing and its repercussions in the loss of fertile soils, which are more appropriate for agriculture use. Also, soil sealing increases flood risk. The main objective is to estimate soil loss by sealing in the Guadarrama River Basin (Madrid, Spain) between 1961 and 2011. The combination of digital processing (Normalized Difference Vegetation Index (NDVI), principal components and convolution filters) of satellite imagery with the digital terrain model helps to detect risk areas and allows quick updating of sealed soil mapping. The supervised classifications of the images were used to estimate the actual soil loss by sealing (9% in 2011) in the Guadarrama River Basin and the types and agrologic classes that have been lost. Soil loss occurs to a greater extent in highly permeable soils (sands) and in the most fertile soils. The main sealed soil associations are luvisols (alfisols), regosols (entisols) and cambisols (inceptisols). Full article

Numerous outbreaks of Escherichia coli O157:H7 have been linked to the consumption of leafy vegetables. However, up to the present, little has been known about E. coli O157:H7’s adaptive responses to survival on actively growing (and thus responsive) plants. In this study, whole genome transcriptional profiles were generated from E. coli O157:H7 cells (isolate Sakai, stx-) one hour and two days after inoculation on the leaves of growing butterhead lettuce, and compared with an inoculum control. A total of 273 genes of E. coli O157:H7 Sakai (5.04% of the whole genome) were significantly induced or repressed by at least two-fold (p < 0.01) in at least one of the analyzed time points in comparison with the control. Several E. coli O157:H7 genes associated with oxidative stress and antimicrobial resistance were upregulated, including the iron-sulfur cluster and the multiple antibiotic resistance (mar) operon, whereas the Shiga toxin virulence genes were downregulated. Nearly 40% of the genes with significantly different expression were poorly characterized genes or genes with unknown functions. These genes are of special interest for future research as they may play an important role in the pathogens’ adaptation to a lifestyle on plants. In conclusion, these findings suggest that the pathogen actively interacts with the plant environment by adapting its metabolism and responding to oxidative stress. Full article

The paper addresses issues related to the citrus waste valorisation process and its inherent uncertainties from the perspective of a new and innovative firm. Thus, we investigate the relevance/role of a business plan analysis in developing a new business (new biobased value chains) in the case of citrus waste valorisation. We look primarily at the inherent uncertainty associated with the start-up phase of a new business aimed at producing and wholesaling semi-finished products derived from the recovery of citrus waste in southern Italy. In order to do so, we use a qualitative case study approach focusing on a small citrus waste valorisation firm located in Calabria, using Agro Management Development (AMD) as a unit of analysis. The choice of this research setting is not random, given the fact that many companies from the Mediterranean are trying to engage in activities to valorise citrus waste deriving from production value chains. The main findings of our analysis can be summarized as follows: (i) focusing primarily on one area of uncertainty (i.e., market uncertainty) might undermine chances of success, as it could indicate an incomplete business strategy to stakeholders, hence hindering their willingness to commit to a new entrepreneurial initiative; (ii) although a business plan could be an effective way to narrow down uncertainty for a new innovative firm, it should be properly customised in order to address all relevant dimensions of uncertainty. Indeed, an insufficiently developed plan might be counterproductive, revealing (for instance, to possible investors) an inadequate strategy for facing and solving emerging problems, therefore putting the whole business project at risk. Full article

The study introduces a prototype multispectral camera system for aerial estimation of above-ground biomass and nitrogen (N) content in winter wheat (Triticum aestivum L.). The system is fully programmable and designed as a lightweight payload for unmanned aircraft systems (UAS). It is based on an industrial multi-sensor camera and a customizable image processing routine. The system was tested in a split fertilized N field trial at different growth stages in between the end of stem elongation and the end of anthesis. The acquired multispectral images were processed to normalized difference vegetation index (NDVI) and red-edge inflection point (REIP) orthoimages for an analysis with simple linear regression models. The best results for the estimation of above-ground biomass were achieved with the NDVI (R 2 = 0.72–0.85, RMSE = 12.3%–17.6%), whereas N content was estimated best with the REIP (R 2 = 0.58–0.89, RMSE = 7.6%–11.7%). Moreover, NDVI and REIP predicted grain yield at a high level of accuracy (R 2 = 0.89–0.94, RMSE = 9.0%–12.1%). Grain protein content could be predicted best with the REIP (R 2 = 0.76–0.86, RMSE = 3.6%–4.7%), with the limitation of prediction inaccuracies for N-deficient canopies. Full article

Production of arable crops in Switzerland is subsidized for services performed within the Proof of Ecological Performance (PEP) program, the crop protection part of which is based on IPM principles. Within PEP, chemical insect control must rely on those approved insecticides that are deemed harmless for beneficial arthropods. Approved insecticides potentially impacting beneficial arthropods may also be applied, but only if unavoidable and with an official permit. In order to assess the ecological and economic sustainability of this PEP program, a reference insecticide strategy illustrating the current PEP requirements was compared with other strategies. For this purpose, a sustainability assessment taking account of ecotoxicological risks and economic viability in addition to the preservation of beneficial arthropods was performed according to the SustainOS methodology. The results show that the one-off use of Audienz (spinosad) to control cereal leaf beetle (Oulema melanopus)—a key pest in winter wheat—would significantly improve sustainability vis-à-vis the reference (Nomolt (teflubenzuron) plus Biscaya (thiacloprid)). However, in the case of the Colorado potato beetle (Leptinotarsa decemlineata), in potato crops, where Audienz is considered the reference, no alternative would exhibit better sustainability. Moreover, the study shows that strategies using Novodor (Bacillus thuringiensis) protect beneficial species well but have the drawbacks of increased yield risk and higher costs. The conclusions drawn from these analyses allow recommendations for modifications of the PEP requirements for these two pest insects. The SustainOS methodology, a multi-step process combining expert knowledge with quantitative assessments including a sensitivity analysis of key target parameters and a rule-based aggregation of assessment results, yielded valuable insights into the sustainability of different crop protection strategies. Full article

Gram-positive bacteria Bacillus subtilis B068150 has been used as a biocontrol agent against the pathogen Fusarium oxysporum cucumerinum. Cucumber was grown in three soils with strain B068150 inoculated in a greenhouse for 90 days, and the colonization ability of strain B068150 in cucumber rhizosphere and non-rhizosphere soils was determined. Changes in total bacteria and fungi community composition and structures using denaturing gradient gel electrophoresis (DGGE) and sequencing were determined. Colony counts showed that B068150 colonization in the rhizosphere was significantly higher (p < 0.001) than in non-rhizosphere soils. Based on our data, the introduction of B. bacillus B068150 did not change the diversity of microbial communities significantly in the rhizosphere of three soils. Our data showed that population density of B068150 in clay soil had a significant negative correlation on bacterial diversity in cucumber rhizosphere in comparison to loam and sandy soils, suggesting that the impact of B068150 might be soil specific. Full article

Geochemical and biological processes that operate in the soil matrix and on the soil surface are important to the degradation of biosolids in soil. Due to the large surface area of soils it is assumed that the microbial ecology is associated with mineral soil surface area. The total mineral surface areas were determined for soils from eight different fields selected from a long term study (1972–2006) of annual biosolids application to 41 fields in central Illinois varying in size from 3.6 to 66 ha. The surface areas for the soils varied from 1 to 9 m²/g of soil. The biological degradation rates for the eight soils were determined using a biological degradation rate model (DRM) and varied from 0.02 to 0.20/year⁻¹. Regression analysis revealed that the degradation rate was positively associated with mineral soil surface area (1 m²/g produces 0.018 year⁻¹ increase in the degradation rate). The annual soil sequestration rate was calculated to increase from 1% to 6% when the soil total surface area increased from 1 to 9 m²/g of soil. Therefore, land application of biosolids is an effective way to enhance carbon sequestration in soils and reduce greenhouse gas emissions. Full article