Land Evaluation and Suitability
Sina Bigdeli; Heidar Ghafari; Mojtaba Norouzi Masir; Abdolamir Moezzi
Abstract
Introduction: Today, the concept of soil quality (SQ) has been widely used to know the capacity and limitations of soils in different environmental systems. The degree of suitability of land is determined by its capacity to provide services and its flexibility against external conditions. Production ...
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Introduction: Today, the concept of soil quality (SQ) has been widely used to know the capacity and limitations of soils in different environmental systems. The degree of suitability of land is determined by its capacity to provide services and its flexibility against external conditions. Production of plant biomass is one of the most important functions of soil in relation to food security. The share of dry land in Iran's agricultural production, especially wheat, is very significant. So that in terms of area, about half of the total area of agricultural lands, in terms of volume of production, about 10% of all agricultural products and about 30% of the country's wheat production are related to these lands. Therefore, maintaining the soil quality of these lands is very important. The main goal of this research is to model and quantify the soil quality of part of the rainfed agricultural lands of Dezpart city using integrated multivariate analysis and also to determine the minimum effective data set.Materials and methods: This study was carried out in a part of the rainfed agricultural area of Dezpart County. First, 119 soil samples were prepared using the composite method from the soil depth of 0-30 cm. Soil sampling was done in a stratified random manner to include all the different geomorphological units. The geographic location of the sampling points was also recorded. The samples were transferred to the laboratory and their chemical-fertility and physical characteristics include reaction (pH), electrical conductivity (EC), organic matter (OM), total nitrogen, available potassium, absorbable phosphorus, calcium carbonate equivalent (CCE), texture, bulk density, mean weight diameter (MWD) of soil aggregates, soil gravel content and cation exchange capacity (CEC) were measured. Then the soil quality was determined using two datasets of total (TDS) and minimum (MDS), and multivariate analysis method. In this method, by using appropriate scoring functions, a score between zero and one was considered for each member of the data set. Also, a weight coefficient was calculated for each member, and finally, the soil quality index, which indicates its degree of desirability, was obtained by three indices including Nemero (NQI), cumulative weighted index (IQI) and simple cumulative index (AQI). Finally, a spatial variation map of soil quality was prepared using the Inverse Distance Weighting (IDW) method in geographic information system (GIS) software.Results and Discussion: The results of the principal component analysis (PCA) test indicated that there are three main components that cover 78% of the total variance changes. The first component alone accounts for about 41% and the second and third components account for 25% and 12% of the total data variance, respectively. Based on the correlation analysis between soil components and characteristics, five characteristics including organic matter (OM), silt content, gravel, pH and EC were selected as MDS members. Became in the TDS collection, the highest weights related to silt and sand (0.093 and 0.095, respectively) and the lowest weight with 0.050 was assigned to bulk density (BD). In the MDS set, the highest weight was related to organic matter and silt and the lowest weight was related to pH. The soil quality of the region was generally classified as medium based on the two indexes of AQI and WQI. However, the NQI method indicated that the soil quality was low. Among the three selected indices with different functions and data sets, the weighted soil quality index with the minimum data set and nonlinear function (WQI_MDS_NL) was chosen as the superior model due to having a higher sensitivity index (or a larger standard deviation). The spatial soil quality map, which was prepared for this study, showed that approximately 50% of the lands in the region had an average soil quality and 50% had a low soil quality.Conclusion: Organic matter, silt, pH, gravel and EC are the main characteristics to determine the soil quality of the region. In addition, stability of soil aggregates, bulk density and lime are the most important limiting factors of soil quality in the region. Therefore, it is suggested to use appropriate management practices such as conservation tillage and use of organic fertilizers to improve these characteristics.
Ali Monsefi; Mojtaba Norouzi Masir; Yazdan Izadi
Abstract
Introduction: Despite the many benefits of tillage to crop establishment and production in the past, new herbicide and minimum-tillage management systems have drastically changed today's methods of crop production. Although tillage systems are used to increase soil porosity, they are a short-term solution ...
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Introduction: Despite the many benefits of tillage to crop establishment and production in the past, new herbicide and minimum-tillage management systems have drastically changed today's methods of crop production. Although tillage systems are used to increase soil porosity, they are a short-term solution that has negative consequences on surface soil structural stability, surface crop residue, and surface soil organic carbon, which are critical features that control water infiltration and subsequent water transmission and storage in soil. Physical and chemical properties of soil such as organic matter of soil is a key attribute of quality that affects water infiltration and soil aggregation. The use of conservation tillage along with the application of appropriate management methods such as conservation of residues, the use of proper rotation and weed control caused to stabilize the particles of soil, prevent the destruction of soil structure and increase soil organic matter. Therefore, changing the method of tillage systems from conventional to conservation, especially in crop rotation cycles, is inevitable. Our objectives were to summarize these findings and present additional information with particular emphasis on changes physical and chemical characteristics in different soil depths due to adoption of conservation tillage in corn-wheat crop rotation.Materials and Methods: The present study was performed to investigate tillage systems (4 levels including ZT-ZT: Zero Tillage-Zero Tillage; ZT-CT: : Zero tillage-Conventional Tillage; CT-CT: Conventional Tillage-Conventional Tillage and CT-ZT: Conventional Tillage-Zero Tillage) and 4 levels of weed management (including W1: Control; W2: Post-emergence Nicosulfuron herbicide + hand weeded in cultivation of corn and post-emergence Metribuzin herbicide + hand weeded in cultivation of wheat; W3: Pre-emergence Atrazine + post-emergence Nicosulfuron herbicides in cultivation of corn and post-emergence Clodinafop + post-emergence Bromoxynil+MCPA herbicides in cultivation of wheat; W4: Wheat residues as a mulch + post-emergence Nicosulfuron herbicide in cultivation of corn and corn residues as a mulch + Metribuzin herbicide) on some physical and chemical properties of soil depths (D1: 0 -15 and D2: 15-30 cm) in corn-wheat rotation during the 2021-22 croping year in the farms of Shavur Agricultural Service Center of Shush city was implemented as a split-factorial in the form of a randomized complete block design with three replications and 96 samples. Results and Discussion: The results showed that interaction of the studied treatments significant effects of the all studied traits except for soil pH. The minimum of soil bulk density was observed in conventional tillage-zero tillage × Wheat residues as a mulch + post-emergence Nicosulfuron herbicide in cultivation of corn and corn residues as a mulch + Metribuzin herbicide as weed management treatment × 0-10 cm soil depths treatment with an average of 1.390 g/cm3, also, the highest hydraulic conductivity of the soil was obtained in conventional tillage-conventional tillage × pre-emergence Atrazine + post-emergence Nicosulfuron herbicides in cultivation of corn and post-emergence Clodinafop + post-emergence Bromoxynil+MCPA herbicides in cultivation of wheat × 0-15 cm soil depths treatment (with an average of 0.994 cm/h). The highest amount of organic matter (with an average 0.771 percent) and phosphorus and potassium elements was achieved in zero tillage-zero tillage × wheat residues as a mulch + post-emergence Nicosulfuron herbicide in cultivation of corn and corn residues as a mulch + Metribuzin herbicide × 0-15 cm soil depths treatment (with averages of 13.96 and 234.7 mg/kg, respectively). Interaction effects results (tillage system × sampling depth) indicated that highest amount of total nitrogen was achieved in the zero tillage-zero tillage (ZT-ZT) on soil surface layer (0-15 cm sampling depth) with an average 122.0 kg / ha with an increase of 40.1% compared to the other treatment such as zero tillage-conventional tillage (ZT-CT), conventional tillage-conventional tillage (CT-CT) and conventional tillage-zero tillage (CT-ZT) and soil substrate (15-30 cm sampling depth, with an average of 0.87 kg/ha). In addition, the preservation of residues in the form of mulch and the use of post-emergence Nicosulfuron and Metribuzin herbicides led to maintaining the balance of soil pH in the corn-wheat rotation.Conclusion: Steady-state soil chemical and physical properties was greater under zero tillage than under conventional tillage as a result of soil structural improvements associated with surface residue accumulation and lack of soil disturbance. In addition, our data indicate that conservation tillage along with the application of crops residues in corn-wheat crop rotation is a viable management strategy to improve soil quality in the warm, semiarid region of Khuzestan Province. This strategy could lead to high production, minimal negative environmental impacts, and a socially acceptable farming system. Therefore, the use of previous crop residues in tillage systems will have a positive effect on improving the physical and chemical properties of the soil.
