A field experiment was conducted at Horticultural Experimental Farm, Assam Agricultural University, Jorhat during the year 2015–17 to assess the impact of boron fertilization on dynamics of boron fractions in soil and crop yields in cauliflower–cowpea–okra cropping sequence. Five levels of boron (0, 0.5, 1.0, 1.5 and 2.0 kg ha⁻¹) along with the recommended dose of NPK fertilizer were applied in soil in cauliflower once in each 2 years (2015–17) of experimentation to assess the direct effect of boron fertilization, while cowpea and okra were grown as a suceeding test crop to study the residual effects of boron fertilization in the cropping sequence. Among the different levels of boron, the highest content of all the boron fractions in soil was recorded at rate of 2 kg B ha⁻¹ at different crop growth stages for all the three crops. Progressive decrease in content of all the boron fractions with crop ageing was noticed. The content of different boron fractions in soil follows the order readily soluble boron (RSB)<oxide bound boron (OXB)<organic bound boron (ORBB)<specifically adsorbed boron (SAB) <residual boron, respectively. The boron level of 2 kg B ha⁻¹ was found to prominent in increasing the yield in all the crops. In respect of contributions of different boron fractions to yield of crops, oxide bound boron(2.10) was found to be the highest contributor of cauliflower yield, while the residual boron (1.10), contributed the highest to cowpea yield and organic bound boron fraction (1.24) was found to be most prominent contributor of boron in leveraging okra yield.

Geospatial techniques and Multi-Criteria Decision Analysis (MCDA) play a crucial role in the planning and management of land and water resources. GIS-based MCDA technique ‘Catastrophe theory’ has been recently proposed for evaluating groundwater potential. However, the major limitation of ‘Catastrophe theory’ is that only quantitative factors/thematic layers can be used for assessing groundwater potential, though qualitative factors are equally important. To overcome this inherent limitation, a novel GIS-based MCDA approach named ‘Hybrid Catastrophe’ technique is proposed in this study. The ‘Hybrid Catastrophe’ technique integrates the original ‘Catastrophe theory’ with the ‘Analytic Hierarchy Process (AHP)’ to take into account both qualitative and quantitative thematic layers for assessing groundwater potential, thereby improving the reliability and versatility of the original Catastrophe technique. The applicability of ‘Hybrid Catastrophe’ technique is demonstrated through a case study wherein 8 influential thematic layers (both quantitative and qualitative) were considered for assessing groundwater potential. The four quantitative layers were assigned weights based on the ‘Catastrophe theory’ and the remaining four qualitative layers were assigned weights based on the ‘AHP theory’. These thematic layers were integrated in GIS to delineate groundwater potential zones. The ‘Hybrid Catastrophe’ technique yields four groundwater potential zones in the study area: (i) ‘very good’ (covering 16% of the study area), (ii) ‘good’ (54%), (iii) ‘moderate’ (29%) and (iv) ‘poor’ (1%) and its accuracy was found to be 77% that is reasonably high. The proposed ‘Hybrid Catastrophe’ technique is versatile and it can be successfully applied to other parts of the world for evaluating groundwater potential at diverse spatial scales irrespective of agro-climatic, hydrologic and hydrogeologic conditions.

This field investigation was conducted to assess the implication of the direct and residual effect of the applied differential level of boron on the dynamics of the soil chemical properties, nutrient status in soil and yield of crops under cauliflower–cowpea-okra cropping sequence in an Inceptisol of North East India. The imposed treatments comprise five levels of boron viz., 0, 0.5, 1.0, 1.5 & 2.0 kg ha⁻¹ with four replications. To assess the direct effect of boron fertilization in soil, cauliflower crop was grown as a test crop. While for further assessment of concomitant residual effects of boron fertilization, cowpea and okra were grown as a test crop wherein boron fertilization was phased out in both the crops. The recommended dose of NPK fertilizer along with FYM was uniformly applied to all the crops in the cropping sequence. The experimental findings showed that amongst the applied differential levels of boron, application of 2 kg B ha⁻¹ was realized as the most prominent boron dose responsible for increasing the maximum content of soil chemical properties, nutrient status in soil and yield of crops while the control plots recorded the lowest for all the three crops in the sequence. Principal component analysis executed in respect of soil chemical properties and soil nutrient status in cauliflower-cowpea-okra sequence explained the data variation to the tune of 77.03%, 76.52% and 70.74% of the total variability. Similarly, multiple linear regressions performed to figure out the best fitting model showed that response variable potassium attributed the highest up to 52.05% in augmenting yield of cauliflower while nitrogen accounted for 72.04% in cowpea and zinc contributed 89.55% in okra, respectively. Overall, the present findings indicated thatapplication of 2 kg B ha^-1 was found to be the best treatment in improving the soil chemical properties, nutrient status in soil and yield of crops under cauliflower–cowpea- okra cropping sequence.

Field investigations were executed during the year 2015–17 to study the direct and residual effect of boron (B) application on crop yield, nutrient concentrations, nutrient uptake and nutrient use efficiencies in cauliflower–cowpea–okra cropping sequence in an acidic Inceptisol of Assam, India. To assess the direct effect of B fertilization in soil, five differential graded levels/doses of B (0, 0.5, 1.0, 1.5, and 2.0 kg ha⁻¹) were applied using cauliflower as a test crop only. While cowpea and okra were grown as test crop to assess the residual effects of B fertilization, wherein B fertilization was exempted in both the crops. Recommended dose of fertilizers and farmyard manure was uniformly added in soil to the all the crops in the sequence. Results showed that among the differential B levels, the application of 2 kg B ha⁻¹ in the cropping sequence exhibited a substantial yield augmentation up to 23.78, 7.15, and 20.61 t ha⁻¹ in cauliflower, cowpea, and okra, respectively. Nutrient contents in leaves and edible portion of the crops, and nutrient uptake were recorded highest under 2 kg B ha⁻¹ treatments as compared with the rest of other treatments. Also the highest nutrient use efficiencies in all the crops were registered under 2 kg B ha⁻¹. The overall results indicated that crop yield, nutrient content, nutrient uptake, and nutrient use efficiencies can be efficiently improved with the application of 2 kg B ha⁻¹ in the cropping sequence.

For assessing the effect of boron fertilization on the micronutrient concentration in plants, its uptake in edible portion and crop yield in cauliflower–cowpea-okra cropping sequence in an Inceptisol of North East India field experiments were conducted during the year 2015–17 at Horticultural Experimental Farm, Assam Agricultural University, Jorhat. Five graded levels of boron were applied (0, 0.5, 1.0, 1.5, and 2.0 kg ha⁻¹) to cauliflower once in both the years to assess the direct effect of boron fertilization in soil while cowpea and okra were grown as a succeeding test crops to study the concomitant residual effects of boron fertilization in cauliflower–cowpea-okra cropping sequence. Recommended dose of NPK fertilizer along with FYM for each crops were uniformly applied. Among the different levels of boron, experimental findings revealed that application of 2 kg B ha⁻¹ was found prominent in augmenting the highest content of micronutrients in plant parts while the control recorded the lowest content for all the three crops in the sequence. A highly significant positive correlation between the different micronutrients content in edible portion of crops were recorded except copper. Similarly, application of 2 kg B ha⁻¹ exhibited the highest micronutrient uptake in edible portion of crops, crop yield, crop equivalent yield, nutrient use efficiencies, and benefit cost ratio for all the crops in the sequence. Multivariate analysis (PCA) exercised on micronutrients content in edible portion of crops explained up to 97.19% of total variance with two principal components.