Soil pH and electrical conductivity
The soil quality standard parameters are illustrated in Table 2. The pH of all study areas were found ranged in between 7.2 to 7.6 which indicate the slight alkalinity of soils. A pH range of 5.2 to 6.5 is rated by most nutritionists as ideal for the optimum growth of most plants because all essential elements are soluble and available within this range
Brady (1974). It is estimated that the alkaline nature of the soil decreases the solubility of minerals and creates nutrient deficiency in the soil
Iram and Khan (2018).
Wagh et al., (2013e) and
Patil et al (2003) also reported that in alkaline soil, minerals solubility decreased which led to nutrient deficiencies in the soils and in the deficiencies of iron, manganese, zinc, copper
etc., plant growth was limited. Electrical conductivity was useful for the estimation of soluble salt concentrations. Soils with EC below 0.4mS/cm are considered marginally or non-saline
Wagh et al., (2013e). Electrical conductivity was observed maximum in Morena (0.44±0.029 mS/cm) and minimum was observed in Banmore (0.31±0.022 mS/cm) (Table 3). The soils of all three sites (Banmore, Rairu and Malanpur) were found non saline except Morena sites. Pearson correlation coefficient and significance among soil physical and chemical properties are presented in Table 4. Several authors including
Molin and Castro, (2008) and
Chitranshi et al., (2018) had reported strong correlation between clay content and soil electrical conductivity. Similarly in this study soil pH was significant and positive correlated with electric conductivity, sand and silt value at (r=0.99), (r=0.34) and (r=.98) respectively, but it was negatively and insignificant value at (r=
-0.02) correlated with the copper.
Soil texture
Soil texture directly or indirectly influences soil functions such as soil erosion, water availability
Adhikari et al., (2009). The sandy soil can quickly be recharged but its holding capacity is not good. As texture becomes heavier, the wilting point increases because fine soils with narrow pore spacing hold water more tightly than soils with wide pore spacing. In this study soil texture of all sites was noted to have a higher proportion of sand. The texture of the soil is sandy loam. Proportion of sand ranged from 46.0 to 66.0%. The clay content ranged from 12.8±2.6 to 32.8±2.2%. Clay content was very low at just 12.8±2.6% in Morena site soil. Silt content was observed in a range of 21.21±2.1 to 21.24±2.4% in all four soil sites. Soil texture was displayed in table 3.
Augustin and Cihacek (2016) found that sand was negatively correlated with organic carbon and silt was strongly correlated with organic carbon, which reflected greater water holding capacity, which in turn increased plant productivity and carbon sequestration in soil. Similarly, in this study the sand of soil was positively and significantly correlated with silt value at r=0.20 and negatively correlated with clay, organic matter and organic carbon. Silt had a negative correlation with water holding capacity, organic matter and organic carbon.
Water holding capacity
Water holding capacity (WHC) was recorded lowest in Morena (37.2±2.1%) and highest in Rairu (62.1±3.8%). Water holding capacity had negative and significantly correlated with organ carbon, organic matter and silt (r=-0.18), (r=-0.18) and (r=-0.34) respectively, but it was positive and significantly correlated with sand and phosphorus values at (r=0.11) and (r=0.91) respectively.
Organic carbon and organic matter
Organic carbon and organic matter play an important role in soil. The organic carbon was observed highest in Banmore (0.55±0.09%) and lowest was observed in Morena (0.51±0.05%) and was under the normal range as the standard table of soil quality (Table 2 and Fig 2a). Organic carbon is an essential component of soil fertility as it add nutrients for plant growth by maintaining physical and biological health of the soil and also acts as a buffer against harmful substances. The organic matter provides a natural home for millions of bacteriological organisms which aid biological and chemical reactions required for sustaining plant life. It aids moisture retention in the soil, enhances soil aggregation, aeration, aids in reduction of soil erosion and increases nutrient holding capacity of soil. For many living entities the source of carbon is organic matter. Soil consists of various kinds of dead animal, live animal, microorganisms and decay plant material. Those all were dependent on soil for nutrients and energy. Organic matter was observed from ranging 0.86±0.07 to 0.93±0.04% in all four soil sites. Very low organic matter was observed in Morena (0.86±0.07% ) (Fig 2b).
Babalola et al., (2021) also found low organic matter ranging from 1.52 to 1.79%. Pearson’s correlation matrix confirmed there was a strongly positive relationship between soil nutrient and soil organic matter. This finding was in agreement with different individuals
Tufa et al., (2019); Bezabih et al., (2016). Similarly in this study, organic matter and organic carbon had positive and significant correlation with nitrogen, phosphorus, potassium and iron. But it was positive and insignificant correlated with zinc. Organic matter and organic carbon was negative and significant with sand, silt and copper.
Total nitrogen
Soil total N was recorded in all sites ranging from 192.2 to 206.2 kg/ha and was under the normal range from soil quality standard (Table 2). Highest total N was observed in Banmore (206.2 kg/ha) and lowest was observed in Morena (192.2 kg/ha) (Fig 2c).
Tufa et al., (2019) and
Nweke and Nnabude, (2014) and
Singh et al., (2009) reported that total N significantly positively correlated with phosphorus and organic carbon. Similarly, in this study total N had positive and significant correlation with phosphorus, potassium, zinc iron and manganese value at (r=0.07), (r=0.39), (r=0.07), (r=0.16) and (r=0.41) and negative correlated with copper (r=-0.42).
Phosphorus and potassium
Phosphorus was one of the important macronutrients required for the growth and metabolism of the plants. Application of phosphorus is necessary for maintaining a balance between the other plant nutrients and ensuring the normal growth of crops
Wagh et al., (2013e). Phosphorus in soil varies from 11.8 to 13.9 kg/ha and is found to be below the minimum requirement (<28)(Fig 2d) as per the soil quality standard (Table 2). Phosphorus was positively and insignificantly correlated with manganese at (r=0.004) and it was negatively and significantly correlated with zinc and copper value at (r=-0.89) and (r=-0.22) respectively.
From the analyzed soil samples potassium ranges may vary from 249.7 to 275.5 kg/ha (Fig 2e), Potassium present in normal range in soil as per standard soil quality (Table 2).
Dhakad et al., (2017) reported that potassium was significantly and positively correlated with EC (r=0.281) and clay (r=0.245) and non significantly correlated with organic carbon (r=0.167), whereas, negatively correlated with pH (r=-0.089), sand (r=-0.162) and silt (r=-0.033). Similarly in this study potassium was positively and significantly correlated with clay content (r=0.06) whereas negatively correlated with pH (r=-0.91), sand (r =
-0.06) and silt (r=
-0.905).
Copper, iron, manganese and zinc
Copper is one of the vital micronutrients for the plant. Copper was strongly bound to soils and immobile, hence the plant roots were in higher concentration of copper in comparison to other parts of the plant
Wagh et al., (2013e). In the present study the concentration of copper in soil samples was found from 0.11 to 0.33 mg/kg (Fig 2f), in all sampling locations and was above (maximum level>0.4 ) as per soil quality standard (Table 2). Iron was one of the other crucial elements for the growth and development of plants. Iron required for oxidation and reduction of nitrates and sulphate, plant metabolism like protein formation, photosynthesis, electron transport and chlorophyll.
Nasar et al., (2019) mentioned that iron (Fe) significantly improved the yield and quality of crops. The range of iron content in all tested soil sites were found from 4.2 to 4.4 mg/kg and And it was the under normal range of Fe (Fig 2g). Another micronutrients was manganese, it aids in the process of photosynthesis and protein synthesis and also plays an important role in formation of chlorophyll along with iron
(Lindsay and Norwell, 1978). The amount of manganese available to the plant depends upon soil pH, the quantity of organic matter present and degree of aeration. In alkaline soil Mn deficiency may occur because it is less soluble at elevated pH level. Manganese content in the soil from the all four sites ranged from 1.1 to 2.1 mg/kg (Fig 2h). For the growth and development of plants zinc is an indispensable micronutrient. Zinc lacking plants are sensitive to various pathogenic fungal root diseases
(Graham and Webb, 1991). Zinc concentration ranged from 0.6 to 0.7 mg/kg (Fig 2i) normal in quantity as per soil quality standard (Table 2).
Niranjana et al., (2017) study also found the soils were comparatively low to high in iron and manganese contents and were low in copper and zinc contents. Zinc was positively and significantly correlated with copper (r=0.51) and negatively and significantly correlated with manganese and iron value (r=0.87) and (r=0.32) respectively. Copper was positively and significantly correlated with potassium (r=0.23) whereas negatively correlated with iron and phosphorus value at (r=-0.86) and (r=
-0.22) respectively (Table 3). Iron was positively and significantly correlated with potassium, phosphorus and manganese values at (r=0.63), (r=0.02) and (r=0.74).
