Agriculture, Volume 7, Issue 5 (May 2017) – 9 articles

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

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

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

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