Agriculture — Open Access Journal

Globally, it is estimated that 20 million hectares of arable land are irrigated with water that contains residual contributions from domestic liquids. This potentially poses risks to public health and ecosystems, especially due to heavy metals, which are considered dangerous because of their potential toxicity and persistence in the environment. The Villavicencio region (Colombia) is an equatorial area where rainfall (near 3000 mm/year) and temperature (average 25.6 °C) are high. Soil processes in tropical conditions are fast and react quickly to changing conditions. Soil properties from agricultural fields irrigated with river water polluted by a variety of sources were analysed and compared to non-irrigated control soils. In this study, no physico-chemical alterations were found that gave evidence of a change due to the constant use of river water that contained wastes. This fact may be associated with the climatic factors (temperature and precipitation), which contribute to fast degradation of organic matter and nutrient and contaminants (such as heavy metals) leaching, or to dilution of wastes by the river. Full article

Maize is grown on a large area in Germany and there is a growing concern in society about negative environmental effects related to this. The objective of the study was to test the performance of mixtures of maize and climbing beans as an alternative to monocropped maize under different site and management conditions. The effects of sowing density of maize and beans as well as the sowing time of beans on total dry matter (DM) yield and bean DM contribution to the total yield were investigated. Further, various mechanical and chemical weed control methods were tested and the resulting total DM yield was compared with that of a reference treatment (manual weeding). Hardly any consistent yield difference between maize/bean mixtures and monocropped maize occurred. The proportion of beans varied over a wide range among sites and was consistently higher when beans were sown at an early growth stage of maize. Mixtures did not suppress weeds efficiently and at two of the three sites their yield clearly declined with increasing weed coverage in the mixtures. A weed coverage of up to circa 10% may be tolerated, as the corresponding yield reduction is less than 1 t ha⁻¹. Considering the additional effort (i.e., two sowings, high costs for bean seeds, complicated weed control) in managing such mixtures, it can be concluded that maize/bean mixtures can currently hardly be recommended as an alternative to monocropped maize for feedstock production. Full article

Smallholder farmers are the main producers of the world’s food and they will have to increase production by up to 100 percent by 2050 to feed the growing population. This must be achieved while preserving natural resources and that is why sustainable agricultural mechanization (SAM) will be fundamental to the process. SAM is climate-smart and environmentally benign and essentially means no-till conservation agriculture, which requires specific mechanization inputs. Principally, these are seeders and planters capable of penetrating soil surface vegetative cover to deposit seed and fertilizer at the required depth and spacing; and equipment for management of cover crops and weeds. Mechanization is required not only for crop production, but also for processing and along the entire value chain. Mechanization inputs are usually expensive and so specialist service provision will be the indicated way forward. This will need collaboration from both the private and public sectors and will involve public-private partnerships to be developed in one form or another. Given the poor track record of public sector mechanization provision, the delivery of SAM should be firmly in the hands of the private sector that should be committed to SAM principles or otherwise be incentivized to the concept through smart subsidies. Improved information flows via smallholder farmer-friendly innovation platforms; and continuing development and testing of SAM technologies via regional centres of excellence will both be required—especially for sub-Saharan Africa. Full article

Methane (CH₄) and nitrous oxide (N₂O) fluxes were measured from paddy–upland rotation (three years for soybean and three years for rice) with different soil fertility due to preceding compost application for four years (i.e., 3 kg FW m⁻² year⁻¹ of immature or mature compost application plots and a control plot without compost). Net greenhouse gas (GHG) balance was evaluated by integrating CH₄ and N₂O emissions and carbon dioxide (CO₂) emissions calculated from a decline in soil carbon storage. N₂O emissions from the soybean upland tended to be higher in the immature compost plot. CH₄ emissions from the rice paddy increased every year and tended to be higher in the mature compost plot. Fifty-two to 68% of the increased soil carbon by preceding compost application was estimated to be lost during soybean cultivation. The major component of net GHG emission was CO₂ (82–94%) and CH₄ (72–84%) during the soybean and rice cultivations, respectively. Net GHG emissions during the soybean and rice cultivations were comparable. Consequently, the effects of compost application on the net GHG balance from the paddy–upland rotation should be carefully evaluated with regards to both advantages (initial input to the soil) and disadvantages (following increases in GHG). Full article

Since soybean (Glycine max L. (Merr.)) yields greater than 6719 kg ha⁻¹ have only recently and infrequently been achieved, little is known about the soil microbiological environment related to high-yield soybean production. Soil microbiological properties are often overlooked when assessing agronomic practices for optimal production. Therefore, a greater understanding is needed regarding how soil biological properties may differ between high- and average-yielding areas within fields. The objectives of this study were to (i) evaluate the effects of region on soil microbial carbon substrate utilization differences between high- (HY) and average-yield (AY) areas and (ii) assess the effect of yield area on selected microbiological property differences. Replicate soil samples were collected from the 0–10 cm depth from yield-contest-entered fields in close proximity that had both a HY and an AY area. Samples were collected immediately prior to or just after soybean harvest in 2014 and 2015 from each of seven geographic regions within Arkansas. Averaged across yield area, community-level carbon substrate utilization and Shannon’s and Simpson’s functional diversity and evenness were greater (p < 0.05) in Region 7 than all other regions. Averaged across regions, Shannon’s functional diversity and evenness were greater (p < 0.05) in HY than in AY areas. Principal component analysis demonstrated that a greater variety of carbon substrates were used in HY than AY areas. These results may help producers understand the soil microbiological environment in their own fields that contribute to or hinder achieving high-yielding soybeans; however, additional parameters may need to be assessed for a more comprehensive understanding of the soil environment that is associated with high-yielding soybean. Full article

In the Italian agrifood sector, one observes heterogeneity in the types of quality certification processes. This heterogeneity cannot be explained by standard governance theories like transaction costs economics (TCE). We use the governance value analysis (GVA) perspective that synthesizes TCE and a resources-based view (RBV), to suggest that the observed heterogeneity in organizational forms is a result of heterogeneous differentiating strategies that farms have pursued in the face of competitive pricing pressures. To empirically test GVA, data are obtained using a survey methodology on lamb meat produced by local farms in the Abruzzo region of Italy, challenged by price-costs squeeze. Our empirical test evidences the relevance of the adopted approach, enlightening different organizational arrangements, strictly linked to both the strategic positioning and to the farms’ resources and core competencies. Full article

Homegrown fruits and vegetables are gaining popularity in many metropolitan areas with several facets connected to the wider urban agriculture phenomenon. At the same time, the relationship between urban food production and irrigation water is pivotal in terms of resource management. In this paper, we investigated water savings through the collection and use of harvestable rainwater from buildings’ rooftops to irrigate 2631 fruits and vegetables gardens in the urban area of Rome (Italy). The methodology makes use of existing geospatial data and data derived from satellite image classification to estimate food gardens’ irrigation requirements and harvestable rainwater from nearby buildings’ rooftops. The comparison of the annual harvestable rainwater with irrigation needs allowed for computing the proportion of water self-sufficient gardens as well as the amount of gardens whose water needs might be partially fulfilled with rainwater. Statistics were produced by land use type (horticulture, mixed crops, olive groves, orchards, and vineyards) and under the hypothesis that irrigation systems with low and high field application efficiency might be employed. We found that 19% and 33% of the gardens could be water self-sufficient for the low and high irrigation efficiency scenario, respectively. The remaining gardens, by using the available rainwater, could satisfy 22% (low efficiency) and 44% (high efficiency) of the water needs resulting in a reduction in the use of conventional water sources. Full article

Combining technologies for monitoring spatial behaviour of livestock with technologies that monitor pasture availability, offers the opportunity to improve the management and welfare of extensively produced beef cattle. The aims of the study were to investigate changes to beef cattle behaviour as pasture availability changed, and to determine whether Global Navigation Satellite System (GNSS) technology could determine livestock grazing preference and hence improve pasture management and paddock utilisation. Data derived from GNSS collars included distance travelled and location in the paddock. The latter enabled investigation of individual animal interactions with the underlying Normalised Difference Vegetation Index (NDVI) and pasture biomass of the paddock. As expected, there was a significant temporal decrease in NDVI during the study and an increase in distance travelled by cattle (P < 0.001; r² = 0.88). The proportion of time budget occupied in grazing behaviour also increased (P < 0.001; r² = 0.71). Cattle showed a partial preference for areas of higher pasture biomass/NDVI, although there was a large amount of variation over the course of the study. In conclusion, cattle behaviour changed in response to declining NDVI, highlighting how technologies that monitor these two variables may be used in the future as management tools to assist producers better manage cattle, to manipulate grazing intensity and paddock utilisation. Full article

The organic industry continues to expand in the United States (U.S.), with 14,093 organic farms in 2014. The upper Midwestern U.S. has emerged as a hub for organic row crop production; however, the management of these organic row crop hectares heavily relies on tillage and cultivation for weed control. Faced with the soil quality challenges related to these practices, and cognizant of the benefits of conventional no-till practices, organic farmers have shown significant interest in the development of Cover Crop-Based Reduced Tillage (CCBRT) techniques to lessen soil disturbance while achieving successful weed management. To serve this farmer interest, significant research efforts have been conducted in the upper Midwestern U.S., focused on systems-based practices to ensure adequate suppression of weeds, through a combination of agronomic and cover crop species and variety selection. Within this review article, we discuss the agronomic successes that have been achieved in CCBRT using a combination of cereal rye and soybeans, resulting in consistent suppression of weeds while providing fuel and labor savings for farmers, as well as the continued challenges that have persisted with its implementation. Continued investment in research focused on cover crop breeding and management, optimization of CCBRT equipment and fertility management, and a greater understanding of rotation effects will contribute to the further expansion of this technique across organic farms. Full article

Cover crop mulch–based no-tillage (MBNT) production is emerging as an innovative alternative production practice in organic farming (OF) to reduce intensive soil tillage. Although European organic farmers are motivated to implement MBNT to improve soil fertility and achieve further management benefits (e.g., labor and costs savings), low MBNT practice is reported in Europe. Thus, this paper aims to understand the challenges of both farmers and researchers limiting the further adoption of MBNT in organic farming in temperate climates. The primary no-tillage (NT) practices of organic European farmers and findings of organic MBNT studies conducted in Europe are reviewed, focusing on living or mulch cover crop-based NT (LBNT or MBNT) for arable crop production. Major conclusions drawn from this review indicate consistent weed control and an establishment of best practices for cover crop management as the two main overarching challenges limiting adoption. In view of substantial gaps of knowledge on these issues, additional research should focus on cover crop selection and management (species, date of sowing) to increase cover crop biomass, particularly in warmer climates. Lastly, further research is needed to optimize cover crop termination to prevent competition for water and nutrients with cash crops, particularly in wetter northern conditions which promote vigorous cover crop growth. Full article

Soybean field experiments were performed to investigate the weed-suppressing effects of different tillage systems and cover crop mulches at two locations in southwest Germany during 2014 and 2015. The influence of three different tillage systems on weed control efficacy, soybean plant density, and crop yield was determined. In the no-till system (NT), two different cover crops, (rye and barley), were treated by a roller-crimper before soybean sowing. For the reduced tillage system (RT), shallow soil cultivation (7.5 cm depth) using a cultivator after cover crop harvest was performed. The third system was conventional tillage (CT), which used a plow (25 cm depth) without any previous cover crop treatment. Finally, a CT system without weed control was used as a control treatment (C). Weed densities in the field experiments ranged from 1 to 164 plants m⁻² with Chenopodium album (L.), Echinochloa crus-galli (L.) P. Beauv., and Sonchus arvensis (L.) as the predominant weed species. No difference in weed suppression was found between the two cover crops. The highest cover crop soil coverage was measured in the NT treatment. The greatest weed density (164 plants m⁻²) was measured in the untreated control. CT, RT and NT reduced weed density up to 71%, 85%, and 61%, respectively, to C, across both locations and years. Soybean plant density was reduced in NT (−36%) and CT (−18%) based on aimed sown plant density. Highest crop yields up to 2.4 t ha⁻¹ were observed in RT, while NT resulted in lower yields (1.1 t ha⁻¹). Our work reveals the importance of cover crops for weed suppression in soybean cropping systems without herbicide application. Full article

The main environmental stressor of the Baltic Sea is elevated riverine nutrient loads, mainly originating from diffuse agricultural sources. Agricultural practices, intensities, and nutrient losses vary across the Baltic Sea drainage basin (1.75 × 10⁶ km², 14 countries and 85 million inhabitants). Six “Soil and Water Assessment Tool” (SWAT) models were set up for catchments representing the major agricultural systems, and covering the different climate gradients in the Baltic Sea drainage basin. Four fertilizer application scenarios were run for each catchment to evaluate the sensitivity of changed fertilizer applications. Increasing sensitivity was found for catchments with an increasing proportion of agricultural land use and increased amounts of applied fertilizers. A change in chemical fertilizer use of ±20% was found to affect watershed NO₃-N loads between zero effect and ±13%, while a change in manure application of ±20% affected watershed NO₃-N loads between zero effect and −6% to +7%. Full article

Current agriculture is based on external fertilizers that jeopardize soil fertility. Alternative fertilization systems might come from the use of soil-borne bacteria with plant growth enhancing ability. Here, six bacterial strains that produce varying concentrations of indole acetic acid (IAA) were tested individually and in consortia for plant growth promotion and fitness-related traits of Cicer arietinum. The nitrogen fixer Mesorhizobium ciceri consistently increased biomass production and N content. In the absence of this strain, IAA Psedomonas putida and Bacillus megaterium hindered plant growth and fitness-related traits. The application of mixes of the three strains always resulted in better plant performance when M. ciceri was present. Mixes that included a P. putida strain that produced low levels of IAA appeared more likely to promote plant growth than mixes that included P. putida strains that produced high levels of IAA or mixes that included B. megaterium. The low levels of IAA produced by the selected strains, compared to the high IAA-producing strains had a significantly greater positive effect on plant biomass accumulation, flower, pod, and seed production, and total plant nitrogen and nitrogen concentrations in seeds. Full article

In northern Japan, declines in soil nitrogen fertility have occurred in paddy–upland rotation systems with soybean cultivation. A six-year lysimeter experiment was conducted to evaluate the nitrogen budget in paddy–upland rotation (three-year for upland soybean, then three-year for flooded paddy rice) and to clarify the effect of preceding compost application (immature or mature compost over four consecutive years of forage rice cultivation) on the nitrogen budget and soil nitrogen fertility. Available soil nitrogen throughout the experimental period and soybean and rice yields in both compost application plots tended to be higher than those in the control plot. The nitrogen budgets during both soybean and rice cultivation were negative, and the amount of nitrogen loss in both compost application plots tended to be higher than that in the control plot. The nitrogen loss during rice cultivation (−2.3 to −4.3 g N m⁻² year⁻¹) was less than that during soybean cultivation (−9.6 to −14.6 g N m⁻² year⁻¹). Nitrogen loss estimated based on the nitrogen budget agreed well with that estimated based on changes in soil nitrogen storage during soybean cultivation but not during rice cultivation, suggesting underestimation of nitrogen loss from the rice paddy. Full article

This article compares and examines the relationships among agricultural assets, incomes and food security in rural communities of Ghana, Senegal, and Liberia. A total of 1483 rural households were surveyed and data on agricultural endeavors, incomes and food security were collected. The analyses of incomes and agricultural assets show signs of high inequality of resource distribution. In addition, facets of food insecurity were observed among the surveyed households. The study used a multivariate logistic model, then evaluated how agricultural assets affect the food security status of rural households in Ghana, Senegal and Liberia distinctly. Overall, the results show several similarities at country level, but disparities were also noted. In particular, the study outlined significant relationships between technology assets and the food security status of rural households in Ghana and Senegal. However, the logistic model did not show any statistically significant relationship with the rural households surveyed in Liberia. This paradigm suggests critical inter-regional dissimilarities which the study discussed by emphasizing relevant socio-economic features at the country level. Full article

Composted dairy manure (CDM) is among the management practices used in transitioning from a conventional to an organic agricultural system. The objectives of this study are to evaluate the impact of several organic nitrogen (N) sources on: (i) soil organic C (SOC) and soil total N (STN) content; (ii) soil C and N distribution among soil fractions; and (iii) N mineralization. This study was initiated in 2007 on a recently renovated alfalfa (Medicago sativa L.) field located at the Agricultural Research, Development and Education Center near Fort Collins, Colorado. The soil type is a Fort Collins loam (fine-loamy, mixed, superactive, mesic Aridic Haplustalfs). Alfalfa and sainfoin (Onobrychis viciifolia Scop.) were interseeded with the grass mixtures as organic N sources. Three grass treatments were established with and without alfalfa or sainfoin. The CDM was also applied to the grass and to grass-alfalfa mixture at a rate of 22.4 Mg ha⁻¹ in 2008 and at rates of 0, 11.2, and 22.4 Mg ha⁻¹ in 2009. Soil samples were collected from the 0–5 cm and 5–10 cm depths in the fall of 2008 and 2009. Throughout the study period, SOC and STN were significantly influenced by depth, but not by treatment combinations. Averaged across the treatments, SOC was greater by 13.7% in 2008 and 24.2% in 2009 at 0–5 than the 5–10 cm depth. Similarly, STN was significantly higher by approximately 9.4% at 0–5 cm in 2008 and 18.7% in 2009 compared with the 5–10 cm depth. The C and N parameters studied and their distributions among various fractions (mineralizable, slow, and resistant) were influenced by the C and N contents of the added CDM. The low C and N contents of the CDM added in the second year of the study did not contribute to soil C and N build-up. The results generated from this study supported our hypothesis because the quality of CDM addition highly influenced C and N distribution among different fractions. Overall, for a transitioning system, CDM should to be added based on the manure-N content to ensure an adequate amount of N addition. To fully evaluate treatment benefits, a longer study period would be required to allow for system adjustment. Full article

For more than a decade, studies have aimed to adapt the agronomy of organic no-till systems for the environmental conditions of Eastern Canada. Most research on organic no-till practices in Eastern Canada has been conducted in the province of Québec, where 4% of farms are certified organic, and results from these trials have been published in technical reports available in French. The objective of this review was to revisit previous research work on organic farming in Eastern Canada—the majority of which has been published as technical reports in the French language—in order to highlight important findings and to identify information gaps. Cover crop-based rotational no-till systems for organic grain and horticultural cropping systems will be the main focus of this review. Overall, a few trials have demonstrated that organic rotational no-till can be successful and profitable in warmer and more productive regions of Eastern Canada, but its success can vary over years. The variability in the success of organic rotational no-till systems is the reason for the slow adoption of the system by organic farmers. On-going research focuses on breeding early-maturing fall rye, and terminating cover crops and weeds with the use of bioherbicides. Full article

Only 34% of all German farms apply reduced tillage (RT), while approximately 1% of the arable land is under no-tillage (NT). Statistics for organic farming are not available, but the percentages are probably even lower. The development of German organic RT and NT has been strongly driven by pioneer farmers for 40 years, and supported by field trials since the 1990s. The main motive for conversion to RT is increased soil quality, followed by reduced labor costs. NT combined with high-residue cover crops plays only a very small role. Rather, German organic farmers resort to shallow ploughing, a reduced number of ploughing operations in the rotation and/or substitution of the ploughing with non-inversion tillage. In field trials, winter wheat (Triticum aestivum L.) yields were reduced up to 67% by using RT methods compared to inversion tillage treatments due to reduced mineralization and increased weed pressure, both of which are major obstacles that impede the wider adoption of RT and NT by German organic farmers. Improvement of NT and RT (rotations, implements, timing) in organic farming is a task of both agricultural practice and science. A number of conventional farmers who have recently converted to organic farming are already familiar with RT. These farmers will act as a thriving factor to implement their experience after conversion and contribute to further innovations of RT in organic farming. Full article

Cover crop-based, organic rotational no-till (CCORNT) corn and soybean production is becoming a viable strategy for reducing tillage in organic annual grain systems in the mid-Atlantic, United States. This strategy relies on mechanical termination of cover crops with a roller-crimper and no-till planting corn and soybean into cover crop mulches. Here, we report on recent research that focuses on integrated approaches for crop, nutrient and pest management in CCORNT systems that consider system and regional constraints for adoption in the mid-Atlantic. Our research suggests that no-till planting soybean into roller-crimped cereal rye can produce consistent yields. However, constraints to fertility management have produced less consistent no-till corn yields. Our research shows that grass-legume mixtures can improve N-release synchrony with corn demand and also improve weed suppression. Integration of high-residue inter-row cultivation improves weed control consistency and may reduce reliance on optimizing cover crop biomass accumulation for weed suppression. System-specific strategies are needed to address volunteer cover crops in later rotational phases, which result from incomplete cover crop termination with the roller crimper. The paucity of adequate machinery for optimizing establishment of cash crops into thick residue mulch remains a major constraint on CCORNT adoption. Similarly, breeding efforts are needed to improve cover crop germplasm and develop regionally-adapted varieties. Full article

Organic agricultural production has become a major economic and cultural force. However, in water-limited environments the tools used for weed control and nutrient supply, namely tillage and cover crops, may not be environmentally or economically sustainable as tillage damages soil and cover crops use valuable water. Thus, a major challenge has been finding appropriate ways to minimize tillage and terminate cover crops while still controlling weeds and obtaining cover crop ecosystem services. One approach to achieve this is through the economically viable integration of crop and livestock enterprises to manage weeds and terminate cover crops. In this article we (1) review research needs and knowledge gaps in organic agriculture with special focus on water-limited environments; (2) summarize research aimed at developing no-till and reduced tillage in organic settings; (3) assess approaches to integrate crop and livestock production in organic systems; and (4) present initial results from a project assessing the agronomic and weed management challenges of integrated crop-livestock organic systems aimed at reducing tillage intensity in a water-limited environment. The goal of eliminating tillage in water-limited environments remains elusive, and more research is needed to successfully integrate tactics, such as cover crops and livestock grazing to increase organic farm sustainability. Full article