Investigating potential indicators of soil health through microbiome response to environmental and anthropogenic stressors

Traditionally, the analysis of soil health has overlooked the biological component of soil due to poor understanding of connections between the microbiome and empirically measured soil health indicators. The purpose of this study was to assess the effects of environmental and anthropogenic stressors on the soil microbiome, with the aim of identifying measurable soil biological indicators. Chosen soils were examined under distinct conditions to evaluate the effect of selected environmental and anthropogenic stressors on the microbiome. Soil biological responses were analyzed via enzymatic response, microbial functional genes, and microbial community. Environmental factors such as soil moisture and organic matter showed significant influence on the microbiome with each selected biological indicator showing importance. Anthropogenic factors provided various responses dependent largely on the nature of the soil amendment. This study demonstrates that in addition to traditional soil health indicators, soil biological indicators should be included in the process of determining healthy soils

Cross-Disciplinary Analysis of the On-Farm Transition from Conventional to Organic Vegetable Production

This farm-scale analysis of the three-year transition to organic from conventional vegetable production tracked the changes in crop, soil, pest and management on two ranches (40 and 47 ha) in the Salinas Valley, California. Many small plantings of a diverse set of cash crop and cover crop species were used, as compared to only a few species in large monocultures in conventional production. The general trends with time were: increase in soil biological indicators, low soil nitrate pools, adequate crop nutrients, minor disease and weed problems, and sporadic mild insect damage. Some crops and cultivars consistently produced higher yields than others, relative to the maximum yield for a given crop. Differences in insect and disease damage were also observed. These results support the value of initially using a biodiverse set of taxa to reduce risk, then later choosing the best-suited varieties for optimal production. The grower used some principles of organic farming (e.g., crop diversity, crop rotation, and organic matter management), but also relied on substitution-based management, such as fertigation with soluble nutrients, initially heavy applications of organic pesticides, and use of inputs derived from off-farm sources. The organic transition was conducive to both production goals and environmental quality

The Effect of Molasses Application on Soil Biological Indicators and Maize Growth of Different Tillage Soil: A Pot Experiment

Soil enzyme activity and labile carbon (LC) have long been used as soil health indicators. Soil health can be improved by molasses addition resulting in better plant growth and productivity. The effect of molasses on soil biological activity and plant growth under different tillage soil has not been discussed in many studies in Hungary. We assessed two soil types under different long-term tillage practices: conservation tillage (CT), which leaves 30% or more residue on the soil surface, and conventional-ploughing tillage (PT). A pot experiment with maize as the crop was carried out using the composite soil (0-20 cm) of CT and PT; a randomized block design with four replications was employed. Three levels of molasses concentration, 0 g L-1, 0.05 g L-1, and 0.2 g L-1 were applied. LC, dehydrogenase (DHA), β-glucosidase activity, plant height, and dry weight biomass were measured at the end of the experiment (after eight weeks). The results indicated that LC in CT increased by 7.61-21.23% over the increase in molasses concentration. LC concentration was significantly higher in the CT than in the PT soil. β-glucosidase activity increased along with the increase of molasses concentration by 11.42-30.43% in CT and 16.03-56.67% in PT; however, the significantly different appeared only in PT soil. The molasses application affected the DHA as well. The activity of dehydrogenase increases by 39.49-80.76% and 30.43-50.59%, respectively, in CT and PT. Nevertheless, no significance occurred in the tillage system or the molasses concentration. Our study also found that the different molasses concentrations did not affect the plant height and dry weight biomass in CT and PT. However, applying each molasses concentration in CT markedly escalated the plant height and dry weight biomass compared to PT. The enhancement of soil biological activity and plant growth by the molasses application allows a promising strategy for maintaining the soil health of agricultural land

Scoping biological indicators of soil quality Phase II. Defra Final Contract Report SP0534

This report presents results from a field assessment of a limited suite of potential biological indicators of soil quality to investigate their suitability for national-scale soil monitoring

Soil cover improves soil quality in a young walnut forest in the Sichuan Basin, China

The soil quality index (SQI) is based on several key indicators and is used to assess soil quality. More than 250,000 ha of walnut saplings (Juglans regia L.) were planted in previous cropland areas in the Sichuan Basin, China, using a range of soil cover types that may affect soil quality with effects that are unclear. We investigated the effects of white film (WF), black film (BF), shade netting (SN), and maize straw (MS) soil cover types and an uncovered control type (CK) on soil chemical and biological indicators and the SQI in the 0-15 cm soil layer in a young walnut forest in the Sichuan Basin over a 27-month study period. The results showed that all soil cover types increased the soil organic matter (SOM), total potassium (TK), and available potassium (AK) concentrations (p < 0.05), whereas the total nitrogen (TN) and available nitrogen (AN) concentrations were greater only in soils covered by MS than in CK (p < 0.05). The available phosphorus concentrations were 64.1 and 193.2% greater in soils covered by BF and MS treatments, respectively, than in the CK (p < 0.05). The numbers of soil faunal groups (N) were 45.7, 36.4, 37.2, and 101.5% higher in WF, BF, SN, and MS, respectively, than in CK (p < 0.05); the individual numbers (S) were 92.3, 36.2, 100.8, and 154.5% greater in WF, BF, SN, and MS, respectively, than in CK (p < 0.05). The microbial biomass carbon (MBC) was 15.5, 32.3, 45.0, and 77.1% greater in WF, BF, SN, and MS than in CK, respectively (p < 0.05). Redundancy discriminant analysis revealed strong positive interactions between biological indicators (MBC, N, and S) and SOM, AN, and AK concentrations. SOM, TN, AK, S, and MBC were the minimum required variables for the effective assessment of the SQI. All four soil cover types led to an improved SQI (p < 0.05), and MS had the greatest effect on SOM, TN, AN, AP, N, S, MBC, and SQI (p < 0.05). In conclusion, all four soil cover types increased the SOM levels, TK, AK, and MBC concentrations, soil faunal diversity, and SQI. The MS treatment was the most cost-effective and efficient measure to improve soil fertility, ecological function, and overall soil quality in the studied walnut forest

The Effect of Molasses Application on Soil Biological Indicators and Maize Growth of Different Tillage Soil

Soil enzyme activity and labile carbon (LC) have long been used as soil health indicators. Soil health can be improved by molasses addition resulting in better plant growth and productivity. The effect of molasses on soil biological activity and plant growth under different tillage soil has not been discussed in many studies in Hungary. We assessed two soil types under different long-term tillage practices: conservation tillage (CT), which leaves 30% or more residue on the soil surface, and conventional-ploughing tillage (PT). A pot experiment with maize as the crop was carried out using the composite soil (0-20 cm) of CT and PT; a randomized block design with four replications was employed. Three levels of molasses concentration, 0 g L-1, 0.05 g L-1, and 0.2 g L-1 were applied. LC, dehydrogenase (DHA), β-glucosidase activity, plant height, and dry weight biomass were measured at the end of the experiment (after eight weeks). The results indicated that LC in CT increased by 7.61-21.23% over the increase in molasses concentration. LC concentration was significantly higher in the CT than in the PT soil. β-glucosidase activity increased along with the increase of molasses concentration by 11.42-30.43% in CT and 16.03-56.67% in PT; however, the significantly different appeared only in PT soil. The molasses application affected the DHA as well. The activity of dehydrogenase increases by 39.49-80.76% and 30.43-50.59%, respectively, in CT and PT. Nevertheless, no significance occurred in the tillage system or the molasses concentration. Our study also found that the different molasses concentrations did not affect the plant height and dry weight biomass in CT and PT. However, applying each molasses concentration in CT markedly escalated the plant height and dry weight biomass compared to PT. The enhancement of soil biological activity and plant growth by the molasses application allows a promising strategy for maintaining the soil health of agricultural land

Enhanced soil quality with reduced tillage and solid manures in organic farming - a synthesis of 15 years

Demands upon the sustainability of farming are increasing in step with climate change and diversity loss. Organic farming offers a viable approach. To further improve organic management, three strategies with potential to enhance soil quality are being tested in a long-term trial since 2002 on a clay loam in temperate Switzerland: reduced tillage vs. ploughing, solid vs. liquid manures and biodynamic preparations. A synthesis of 15 years reveals an increase in topsoil organic carbon (SOC, +25%), microbial biomass (+32%) and activity (+34%) and a shift in microbial communities with conversion from ploughing to reduced tillage. Soils under reduced tillage are more stratified in SOC and nutrients. Additional application of composted manure has increased SOC by 6% compared to pure slurry application, with little impact on soil microbes. Biodynamic preparations have had a minor impact on soil quality. Fertilisation and biodynamic preparations did not affect yields. Both higher and lower yields were harvested in the reduced tillage system in relation to ploughing. The main yield determinants were N supply and higher weed infestation under reduced tillage. Continuously reduced tillage in organic farming has been proven to enhance soil quality at this site, while also presenting more challenges in management

Environmental research on the new Lincoln University dairy farm

A major challenge to the New Zealand’s growing dairy industry is to achieve an annual productivity gain of 4% in order to remain internationally competitive. However, it is important to ensure that this productivity gain is achieved without significantly comprising the quality and integrity of New Zealand’s “clean and green” environment. There is increasing public concern about the effects of dairying on the environment, both within New Zealand and by our overseas customers. One of the main concerns is the possible threat to the quality of groundwater and surface water, particularly by nitrate, phosphate and microbial contaminants. Nitrate leaching from soil is of concern because of its impact on drinking water quality and the effects that nitrate can have on rivers and lakes. A high nitrate concentration in drinking water is a recognised health hazard and a high concentration in rivers and lakes can cause excessive growth of algae and weeds, which may reduce the fish population. Nitrate leaching also represents a financial cost to the farmer and a loss in soil fertility. The establishment of the new Lincoln University dairy farm is designed to enable us to develop and test practical methods to improve productivity and at the same time protect the environment. The objective of the environmental project on the new Lincoln University dairy farm is to develop best management practices under irrigation which will ensure that the dairy industry’s 4% productivity gain is achieved in a sustainable way, and that the wider environment is protected