Soil Health and Its Improvement Through Novel Agronomic and Innovative Approaches

Soil is an important natural resource providing water, nutrient, and mechanical support for plant growth. In agroecosystem, continuous manipulation of soil is going on due to addition of input, removal of nutrients, changing water balance, and microbial life. These processes affect soil properties (physical, chemical, and biological), and the deviation of these properties from the normal status is controlled by soil buffering capacity and soil resilience. If these changes are beyond the reach of soil resilience, then soil loses its original state, leading to soil degradation. At present, the extent of the degraded area in the world is 1,036 to 1,470 million ha. This urges the need for maintaining soil health rather than the mere addition of input for crop production. Soil health is an integrative property that reflects the capacity of soil to respond to agricultural intervention, so that it continues to support both agricultural production and the provision of other ecosystem services. Maintaining the physical, chemical, and biological properties of soil is needed to keep it healthy, and this is possible through the adoption of different agronomic approaches. The diversification of nutrient sources with emphasis on organic sources, adoption of principles of conservation agriculture, enhancement of soil microbial diversity, efficient resource recycling through the integrated farming system, and amendment addition for correcting soil reactions are potential options for improving soil health, and are discussed in this review. This article reviewed the concept of soil health and its development, issues related to soil health, and indicators of healthy soil. At the same time, the impact of the ill health of the soil on crop productivity and resource use efficiency reported in different parts of the world in recent years are also reviewed. The agro-techniques such as green and brown manuring in arable land and agroforestry on degraded and marginal land were followed on piece meal basis and for economic gain. The potential of these and several other options for maintaining soil need to be recognized, evaluated, and quantified for their wider application on the front of soil health management avenues. The use of crop residue, agro-industrial waste, and untreated mineral or industrial waste (basic slag, phosphogypsum, etc.) as soil amendments has a huge potential in maintaining healthy soil along with serving as sources of crop nutrition. The review emphasizes the evaluation and quantification of present-day followed agro-techniques for their contribution to soil health improvement across agro-climatic regions and for wider implications. Furthermore, emphasis is given to innovative approaches for soil health management rather than mere application of manures and fertilizers for crop nutrition.

Effect of conservation agriculture practices on the resilience of Mediterranean soils to the predicted seasonal drought events

<p>How climate change will affect soil functioning is a major concern, especially in Mediterranean agrosystems, where, according to climate change projections, the occurrence of extreme temperatures and drought events will be increased. The main objective of our experiment was to evaluate the effect of land management (tillage system) on soil resilience against a simulated dry-rewetting cycle. Soil samples were collected from an in-situ field experiment established in 2008 in the Guadalquivir Valley, where conservation agriculture practices have been tested. Three different land management practices under a typical Mediterranean wheat-legume rotation system were compared: 1) traditional tillage (TT), 2) minimum tillage (MT) and 3) no-tillage (NT). Following our hypothesis, conservation agriculture practices (reduced tillage and no-tillage) may allow a more mature soil microbial community by reducing soil perturbation, and this would result in higher resistance of soil functioning against drought periods. Soil enzyme activities (β-glucosidase, phosphatase, acetylglucosaminidase, aminopeptidase, and dehydrogenase activities), microbial functional diversity (Microresp method), and soil DNA concentration (as an index of microbial biomass) were analyzed in a base-line sampling. Afterwards, a dry-rewetting cycle was simulated under controlled conditions. 8 subsamples of 50g from each soil sample were hydrated to reach 70% of each soil water holding capacity (WHC) and kept in those conditions for a pre-incubation period of 15 days. After this period, half of the replicates were let dry for 12 days (drought), while the others were maintained at 70% WFC (controls). Finally, all replicates were rehydrated again to the initial water content during a 14 days rewetting period. During this cycle, soil respiration rates were periodically measured to study the evolution of soil microbial activity. Our results showed that initial respiration rates were slightly higher in MT compared to NT (p<0.1), likely due to higher organic C and N content in the MT soils. Drought extremely reduced respiration rates in the three treatments, but the results did not show a clear pattern among treatments. During the rewetting period, respiration rates were significantly higher in drought samples in comparison with the controls, while no significant differences were found for the land management treatments. Besides, land management practices did not have a significant effect on soil DNA concentration, functional diversity of the microbial community, or enzyme activities. To conclude, the absence of a clear effect of land management practices on soil resilience to drought may be due to the experimental conditions. An in-situ experiment will allow us to determine if tillage reduction enhances soil resilience to moisture stress.</p>

EFFECT OF COMPOST DOSES ON SOIL RESILIENCE IN PALU VALLEY

Applying organic matter to the soil surface is an effective effort to increase soil resilience in the Palu valley, which is classified as low. This study aimed to determine: 1) the effect of several doses of compost on the physico-chemical properties of the soil, 2) the correlation between the percentage of organic carbon and total nitrogen in the soil to several physico-chemical properties of the soil. The research was based on a randomized block design in a greenhouse of the Faculty of Agriculture, Tadulako University, Palu. Compost uses raw materials for plantain stems (Musa textilia) and leaves of Gamal (Gliricidia sepium). The compost doses used in the experiment consisted of 0%, 1%, 2%, 3%, 4%, and 5% of the weight of air-dry soil, respectively. The treatment was repeated three times. The results showed that compost application significantly affected soil content weight, total porosity, saturated hydraulic conductivity, field capacity moisture content, percentage of organic carbon, total nitrogen, and cation exchange capacity. The correlation test results showed a powerful relationship between the percentage of organic carbon or total soil nitrogen to other soil physico-chemical properties observed in the experiment.

Measure soil resilience after reclamation of open pit dump in semi-arid area

<p>The main work of soil reclamation in coal mine area is to recover the structure and function of soil, which is the key factor for the restoration of mine damaged ecosystem. The calculation of soil resilience is an index to measure the stability of ecosystem, which provides guidance for the sustainability of soil management. As the case of Heidaigou open pit mine in Mongolia, the soil restoration of waste dump in 1995, 2000, 2008 and 2015 is taken as the research objects. The field investigation and soil quality experiment data are used to compare and analyze between the reclamation soil and original soil. The soil resilience of waste dump of open pit mine is measured by principal component analysis and structural equation model. The results showed:  (1) The volume density of reclaimed soil was larger, and the soil particle size did not show obvious vertical layered distribution. The degradation of soil nutrients, the low level of soil fertility, the accumulation of soil alkaline hydrolysis nitrogen content and organic matter, and the utilization of plant roots to nutrients were low. The biodiversity and activity of soil decreased. (2) Quantitative evaluation of soil resilience was divided into four dimensions: soil structure stability, soil water retention capacity, soil fertilizer retention capacity, and soil biological activity. Soil clay particles, silt particles, median diameter, and sand particles contributed 81.609% to main component for soil structure stability. Surface water content, deep water content, bulk density, calcium carbonate contributed 82.379% to main component for soil water retention capacity. Soil organic, alkaline nitrogen, total nitrogen, pH, total potassium, total phosphorus, available phosphorus contributed 85.39% to main component for soil fertilizer retention capacity. Soil urease, alkaline phosphatase, invertase activity, microbial diversity Simpson index, richness Chao index, litter quality, pH contributed 87.373% to main component for soil biological activity. (3) Soil resilience was measured by four aspects: soil structure stability, soil water holding capacity, soil fertilizer holding capacity and soil biological activity. The average soil resilience value was 0.37, 0.33, 0.26, 0.18 in 1995, 2000, 2008, 2015, respectively. The average soil resilience was 0.75 in original soil. Soil biological activity had the positive impact on soil resilience, with an influence coefficient of 0.66. The water retention capacity and fertilizer retention capacity had coefficient of 0.44 and 0.37 on soil resilience.</p>

Soil resilience and management of former sugarcane (Saccharum officinarum L.) lands on the Naparima Peneplain, Trinidad and Tobago

The lands of the Naparima Peneplain, Trinidad and Tobago, are an invaluable resource with multiple land use characteristics including agricultural diversification. Sections are classified as Class V soils, non-resilient with minimum recovery over the medium term, and as Class IV soils, slightly resilient with improvements in medium term resulting in significant land management and land use changes. These lands were under sugarcane cultivation for centuries, from the colonial era until the closure of the sugar factory in 2003. Since then, as in so many other Caribbean territories, the land has been ear-marked for agricultural diversification and made available to small farmers for the production of commodities for the domestic market. Land use changes in the post-sugarcane era have resulted in approximately 14,000 hectares becoming available for possible agricultural diversification. However, the positive impact on domestic food supply that was anticipated has not materialized. A land resource study was conducted in 2012–2014 in the La Gloria and Cedar Hill sections of Caroni (1975) Ltd lands on the Naparima Peneplain, to determine the effect of long-term sugarcane (Saccharum officinarum L.) cultivation on land degradation and soil resilience by comparison with data from historical records and to make recommendations on the way forward. Assessment of land use, chemical and physical soil properties, and extent of soil erosion, comprised the study. The most severe land management factor was identified as chronic and widespread soil erosion, especially in Cedar Hill, with additional problems of subsoil exposure, soil slumping and movement. Soil erosion studies (Universal Soil Loss Equation (USLE)) indicate estimates of 35–74 t/ha affecting 75% of the lands. Historical records on soil physical indices such as bulk density, clay percentage in the profile and available water, revealed that these parameters were stable over the period 1977–2014. However, chemical indices, inclusive of organic carbon, nitrogen and pH, reflect significant decline correlated with reduced soil fertility and land abandonment. While identifying stable soil resilience indices is valuable, the immediate problem is the correction of soil erosion, which results in considerable land abandonment. Therefore, it is recommended that the land be restored to an acceptable level of soil fertility, specifically with respect to its organic matter content, and that infrastructural adjustments be made to stop or greatly minimize soil erosion so that these lands could be used to contribute to national food security as envisaged.

Soil Resilience and Sustainability of Semi-Arid and Humid Tropical Soils of India: A Commentary

Soil is a dynamic and living natural resource, which supports to produce goods and services of value to humans but not necessarily with perpetual ability against the degradative processes. It is well known that soil formation is a slow process, and a substantial amount of soil can form only over a geologic timescale. Soil misuse and extreme climatic conditions can damage self-regulating capacity and give way to regressive pedogenesis (Pal et al. 2013), and thus might lead to the soil to regress from higher to lower usefulness and or drastically diminished productivity. Such an unfavorable transformation of soils is termed as ‘soil degradation'. However, soils do have an inherent ability to restore their life support processes if the disturbances created by anthropogenic activities are not too drastic and sudden, and mitigated with enough time is allowed for life-support processes to restore themselves. This intrinsic ability of soils to regenerate their productivity is called resilience (Szabolcs 1994). Therefore, soil resilience is the ability to bounce back or return to normal functioning, after adversity, for sustainable productive purposes.