Comparison of methodolgies of soil quality indices (SQI) for sodic soil

Abstract

Soil degradation and the use of urban biosolid wastes to soil restoration have an economic, social-environmental and health impact. Therefore, there is interest worldwide in the use and comparison of methodologies to establish soil quality indexes (SQIs) based on physical, chemical, and biological indicators of soils. Considering that more than 60% of the territory in the Bajío region of Mexico in the State of Guanajuato is affected by some type of soil degradation, three methodologies for the establishment of SQIs—additive, weighted and unified weighted indexes—were compared in this study to evaluate the short-term effects—30 days—of the addition of biosolids as soil improvers. The methodologies were applied in experiments on carbon (C) and nitrogen (N) mineralization dynamics in a sodic agricultural soil. The ammonium indicator (N-NH4+) was established as the one that is most related to the quality of the soil. The additive and unified weighted indexes differentiated the level of soil quality with respect to time and treatment. The developed SQIs can be used for short-term assessment of the quality of agricultural soils under amendment addition treatments with biosolids or similar organic products.

Analyzing the Impact of Intensive Agriculture on Soil Quality: A Systematic Review and Global Meta-Analysis of Quality Indexes

“…In order to address soil deterioration, techniques such as zero or conservation tillage have been developed, alongside the use of organic amendments such as manure, biosolids, and composts. These techniques aim to increase soil OM and improve soil physicochemical and biological conditions [11,13,32,33], which allows for the recovery of the soil structure and its proper functioning, in order to carry out basic ecological functions such as nutrient cycling, water supply, C-CO 2 fixation, and OM mineralization [34]. To understand the impact of soil management techniques, it is important to have methods that accurately assess the initial conditions of the soil.…”

“…There are different types of methodologies for the establishment of SQIs, such as the following: expert opinion indexes (SQI EO ), which use the empirical knowledge of trained personnel for the selection and degree of importance of the indicators to be included [11,12]; additive indexes (SQI A ), which analyze the indicators, considering them to have linear behavior [11,12]; weighted additive indexes (SQI W ), which use weights previously established by experts in the indicators to be included [11,12]; Nemoro indexes (SQI N ), used in soil quality studies around the world [11,12]; and unified weighted additive indexes (SQI U ), which establish the weights of the indicators based on statistical techniques. SQI W and SQI U are the most used in agricultural soils, and their application depends largely on those responsible for monitoring [11,12]. However, the SQI W methodology can result in the selection of indicators that do not correlate with the problem or phenomenon to be studied, since it is based on indicators previously established.…”

Compost Quality Indexes (CQIs) of Biosolids Using Physicochemical, Biological and Ecophysiological Indicators: C and N Mineralization Dynamics

“…M was maintained throughout the experiment at 40-60% of WHC by periodic manual application of sterile distilled water. Aeration was carried out by turning and manual-mechanical mixing every three days for the first two weeks, thereafter, the aeration process was carried out in periods of 8 + and SOC were previously described in Section 2.2. The WHC was determined using the methodology described by Nannipieri [25].…”

“…Therefore, the indicators obtained and their applicability in the monitoring of composting systems highlight the importance of establishing the biosolids application dose with respect to their N concentration and their biological functionality-enzymatic activity. Previous studies carried out by the research group related to the application of biosolids to soils, were already incapable of monitoring indicators related to the N cycle and the diverse microbial activities of the soil [5,8,10]. Finally, the obtained CQIs are shown below:…”

“…Improved soil conditions have been reported following the addition of BS, through improved water holding capacity (WHC) and improved soil structure, as well as increased fertility from the addition of easily degradable C and N compounds [7]. The addition of BS to degraded soils increases plant cover, microbial activity and diversity, which are stimulated by the addition of easily degradable OM, allowing better nutrient cycling in the soil [5,[8][9][10].…”