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The objective of the study is to measure the ultrasonic velocity, density, and viscosity of the plant-growing media prepared with different combinations of soil texture and moisture absorbent growing media. Four groups of soil texture (S1: loamy; S2: clay; S3: sand; and S4: pure sand/quartz) along with five moisture absorbent growing media (G1: coco peat; G2: vermiculite; G3: vermicompost; G4: sawdust; G5: hydrogel; and G6: control—soil alone) were used. Results showed that these acoustic detection technologies showed significant difference in soil physical properties. Ultrasonic studies described the nonlinear variations in the acoustical parameters among the different soil texture types and growing media tested. Moreover, the values of the acoustical parameters indicated the soil texture when added with any of the moisture absorbent media; water-holding properties of the soils are significantly varied and it suggests that even sand with less water-holding property can be used as a plant-growing medium, with the support of any of these moisture absorbent media (especially hydrogel). The lowest velocity was observed in pure sand alone. However, as the plasticity and the clay content of the soil increases, the porosity also increases and resulting in a decrease in the densities and increase in water content of the soil. Similarly, in heavy-textured soils (high clay content), addition of moisture absorbent media was negative. The comparative study of acoustical properties was made to elucidate the inter-ionic interactions in solutions of soil texture, and growing media and which help to choose the right combination of soil texture and moisture absorbent growing media. The results confirmed that the ultrasonic technique was a powerful and effective tool to investigate the molecular interaction between soil texture and moisture absorbent growing media and helpful for irrigation management.

BACKGROUND Humic acid is a promising natural resource to be utilized as an alternative for increasing soil fertility and crop production. A field experiment was conducted on the loamy sand soil at the Central Coffee Research Institute research farm, Karnataka, India for 2 years to evaluate the influence of humic acid on yield and bean quality of coffee with six treatments. The treatments comprised of recommended dose of fertilizer (RDF), humic acid soil application and foliar spray along with nutrient mixture and growth hormones. RESULTS The data of the yield attributes of coffee revealed that the highest total nodes per branch, crop nodes per branch, flower buds, total number of fruits per branch and fruit set percentage of 17.45, 9.4, 208.65, 153.31 and 3.28, respectively, were recorded by T6 , which consists of RDF + humic acid granules at 10 kg acre-1 + nutrient mixture spray (1 kg urea, 1 kg SSP, 0.75 kg MOP, 1 kg ZnSO4 + 75 mL Planofix 200 L-1 + humic acid at 600 mL 200 L-1 as foliar application 25 days after blossom) during the both years of study. Humic acid application significantly improved the yield in both seasons of research. The same trend was observed in coffee bean quality and tree nutrients status. Postharvest nutrient status in the soil did not show any significance. CONCLUSIONS The study emphasized that application of humic acid as soil and foliar application improves the yield attributes, yield and quality of coffee apart from the economic profitability. © 2020 Society of Chemical Industry.