Changes in soil fertility status due to micronutrients under different methods of mustard establishment in black soils of Madhya Pradesh

Introduction

Indian mustard (Brassica juncea L.) is a major oilseed crop of India, which contributing edible oil and strengthening rural economy. Despite of its significance, mustard yield is constrained due to nutrient imbalance and inadequate crop management practices. Various mustard growing areas, deficiency of secondary and micronutrients, particularly sulphur and boron have been proliferated due to continuous cropping and imbalance use of nutrients. Sulphur and boron deficiency are widely recognized as a yield-limiting factor in Indian soils, which adversely affecting protein synthesis, oil content as well as seed quality in mustard. The physical and chemical properties of soil play an important role in nutrition uptake and subsequently in growth and yield of crop. Sulphur is an essential component of amino acids, vitamins, enzymes, and is vital for oil synthesis and seed protein content in mustard. (Sharma et al., 2008) [7] . Boron, although needed in less amounts, is crucial for cell wall synthesis, pollen viability, and reproductive development; its lack frequently leads to inadequate blooming and decreased siliqua production, ultimately reducing seed yield. Evaluating soil chemical characteristics under different fertiliser levels and establishment procedures is crucial for formulating sustainable and site-specific nutrient management strategies. A comprehensive study of mustard response to varying levels of sulphur and boron with different establishing methods would yield insights for optimising nutrient use efficiency while maintaining soil health and productivity.

Materials and Methods

A field experiment was conducted at Research Farm, Department of Agronomy, Jawaharlal Nehru Krishi Vishwa Vidyalaya, Jabalpur (MP) during rabi seasons of 2022-23 and 2023-24 in order to determine the changes in soil fertility status due to micronutrients under different methods of mustard establishment in black soils of Madhya Pradesh. A total of 24 treatment combinations were laid out in a splitsplit plot design with three replications. Treatment consisted of crop establishment methods (M 1: Direct seeding and M 2: transplanting) in main plots and four levels of (S 1: control, S 2: 20 kg S ha -1 , S 3: 30 kg S ha and S 4: 40 kg ha -1 ) in sub plots and three levels of boron (B 0: control, B 1: 1 kg B ha -1 and B 2: 2 kg B ha -1 ) in sub-sub plots. Mustard variety RH-725 were used for sowing. The recommended dose of fertilizer 80:40:40 kg NPK ha -1 were given to the crop. Sulphur and boron was applied in soil as basal as per the treatments. In order to study the physical chemical propertied, soil sample were collected from different places randomly from experimental plot with the help of wooden spade to a depth of 0-15 cm prior to start of experiment. The soil sample representing the main plot, sub plot and sub-sub plot were taken and analysed in laboratory for physical and chemical properties. Bulk density (g cm -3 ) Core sample (Black et al., 1965) [1] 1.30 2 Soil pH 1:2.5 (Soil water ratio) Glass electric pH meter (Piper, 1966) [6] 7.06 3

Electrical conductivity (dSm -1 ) Solu-bridge method (Black, 1965) [1] 0.26 4 Organic Carbon (%) Chromic acid rapid titration method (Walkley and Black, 1934) [9] 0.68% 5

Available Nitrogen (kg ha -1 ) Alkaline permanganate method (Subbiah and Asija, 1956) [8] 262.20 6

Available Phosphorus (kg ha -1 ) Calorimeter method (Olsen et al., 1954) [5] 12.80 7

Available Potassium (kg ha -1 ) Flame photometer Method (Jackson, 1973) [3] 286.40 8

Available Sulphur (kg ha -1 ) Turbidimetric procedure (Chesnin and Yien, 1951) [2] 9.30 9

Available boron (mg ha -1 ) Azomethine-H method (John et al. 1975) [4] 0.57

Results and Discussion

Effect of crop establishment methods

The data presented in Table 2 showed that effect of crop establishment methods on soil physical and chemical properties with respect to soil bulk density, pH, electrical conductivity and organic carbon content was found nonsignificant in post-harvest soil. However, the higher values of bulk density (1.31 g cm -3 ), pH (7.13), electrical conductivity (0.29 d S m -1 ) and organic carbon (0.70%) was found in transplanting of crop through the difference were non-significant. Data in relation to status of available nitrogen, phosphorus, potassium, sulphur and boron were determined in postharvest soil were present in Table 3. The results of study reveal that the soil status of N, P and K numerically improved over their initial values in the post-harvest soil.

The status of available nitrogen, phosphorus and potassium, improved over the years. However, the differences among the treatments were found to be non-significant.

Effect of sulphur

The effect of levels of sulphur on soil bulk density, pH, electrical conductivity and organic carbon content in postharvest soil was found non-significant. The highest values of soil bulk density (1.28 g cm -3 ), pH (7.14), EC (0.30 dS m - 1 ) was observed in control while 40 kg S ha -1 registered the highest organic carbon (0.69%). However, increasing levels of sulphur from 0 to 40 kg S ha -1 decreased the soil pH, while increased the organic carbon as compared to their initial values. Further, data showed that higher values of available nitrogen 281.23 kg ha -1 was recorded in 40 kg S ha -1 in post-harvest soil and significantly superior over rest levels of sulphur (Table 3). The 40 kg S ha -1 was also found to be statistically at par with 30 kg S ha -1 . The lowest available nitrogen of 260.54 kg ha -1 in post-harvest soil was recorded in control treatment. The available phosphorus and potassium did not changed significantly due to sulphur level during the study period in post-harvest soil. The data pertaining available sulphur and boron were also presented in Table 3. The highest value of available sulphur of 11.52 kg ha -1 was observed under 40 kg S ha -1 while lowest values of available sulphur (10.05 kg ha -1 ) was observed in control plots. It was also observed that available sulphur gradually increased with an increase in dose of sulphur. These findings are in accordance with the findings of Singh et al., (2017). The available boron did not changed significantly due to sulphur level during the study period in post-harvest soil.

Effect of boron

The result of study reveal that effect of levels of boron on soil bulk density, pH, electrical conductivity and organic carbon content in post-harvest soil were found nonsignificant (Table 2). The highest value of soil bulk density (1.32 g cm -3 ), pH (7.14) and electrical conductivity (0.29 dS m -1 ) was recorded in control, while minimum pH (7.06) and electrical conductivity (0.26 dS m -1 ) was recorded under application of boron @ 2 kg ha -1 . Whereas, highest value of organic carbon (0.69%) was recorded in of boron @ 2 kg ha -1 . Increasing the levels of boron 0 to 2 kg ha -1 decreased the soil pH, EC but increased the organic carbon content. The data presented in Table 3 indicated that various boron levels had significant effect on status of available boron in post-harvest soils except available phosphorus potassium and sulphur which were non-significant. The available phosphorus, potassium and sulphur in post-harvest soil did not show any significant variations due to boron levels. The results of study reveal that the status of boron in postharvest soils were changed significantly due to change of levels of boron. Application of boron @ 2 kg ha -1 registered significantly highest values of available boron (0.67 mg ha - 1 ) in post-harvest soil. Whereas, lowest values of available boron (0.62 mg ha -1 ) was found in control.

Conclusion

Based on two years field study it is concluded that crop establishment methods direct seeding and transplanting proved equally good for soil properties. Whereas, levels of sulphur and boron both had the significant positive effect on status of available sulphur and boron after two years of experimentation. Thus, it may be recommended that sulphur and boron both the nutrients are necessary for maintaining nutrient status in soil under mustard cultivation.

References

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