Production and characterization of enriched NADEP composts and evaluation of manurial value

Abstract

The study entitled " Production and characterization of enriched NADEP composts and evaluation of manurial value" was carried out during 2023-24 in the Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani. The objective of the study was the production and characterization of enriched NADEP composts using different organic sources and the evaluation of manurial value using the tomato variety Vellayani Vijai as test crop. The study comprised of two parts viz: the production and characterization of enriched NADEP composts from different organic sources and a field experiment for evaluating the performance of the enriched NADEP compost. NADEP compost was prepared in NADEP tanks using two commonly available aquatic weeds, yellow velvet leaf (Limnocharis flava) (S1) and water hyacinth (Eichhornia crassipes) (S2). Banana pseudostem was added to the aforesaid aquatic weeds in a 1:1 ratio. The matured composts were then enriched with minerals like calcium apatite (M1), epsom salt (M2) and calcium apatite + epsom salt (M3) at rate of 2 per cent in different combinations. The design followed was a Completely Randomized Design with 12 treatments and 3 replications. The treatment combinations were T1- NADEP compost prepared from 1:1 mixture of L. flava and banana pseudostem enriched with calcium apatite, T2- NADEP compost prepared from 1:1 mixture of L. flava and banana pseudostem enriched with epsom salt, T3- NADEP compost prepared from 1:1 mixture of L. flava and banana pseudostem enriched with calcium apatite and epsom salt, T4- NADEP compost prepared from 1:1 mixture of E. crassipes and banana pseudostem enriched with calcium apatite, T5- NADEP compost prepared from 1:1 mixture of E. crassipes and banana pseudostem enriched with epsom salt, T6- NADEP compost prepared from 1:1 mixture of E. crassipes and banana pseudostem enriched with calcium apatite and epsom salt, T7 - NADEP compost prepared from 1:1 mixture of L. flava and E. crassipes enriched with calcium apatite, T8- NADEP compost prepared from 1:1 mixture of L. flava and E. crassipes enriched with epsom salt, T9- NADEP compost prepared from 1:1 mixture of L. flava and E. crassipes enriched with calcium apatite and epsom salt, T10- NADEP compost prepared from 1:1:1 mixture of L. flava, E. crassipes and banana pseudostem enriched with calcium apatite, T11- NADEP compost prepared from 1:1:1 mixture of L. flava, E. crassipes and banana pseudostem enriched epsom salt and 166 T12- NADEP compost prepared from 1:1:1 mixture of L. flava, E. crassipes and banana pseudostem enriched with calcium apatite and epsom salt. To all the treatments (T1 – T12) zeolite was added at a rate of 0.5 per cent. The physico-chemical and biological properties of the produced composts were analysed. Based on the analyzed parameters like major and minor nutrients, enzyme activity, C:N ratio, fertilizing index and clean index the best six composts selected for field experiment were T3, T6, T7, T9, T10 and T12. Among these, T9 (NADEP compost prepared from 1: 1 mixture of L. flava and E. crassipes enriched with calcium apatite and epsom salt) was selected as the best compost with the highest values of most of the macro and micronutrients, N (3.03 %), P (0.62 %), K (1.80 %), Ca (0.32 %), Mg (0.26 %), S (30.00 mg kg-1), B (44.97 mg kg-1), Fe (1.40 %), Mn (179.00 mg kg-1), Zn (56.19 mg kg-1) Cu (26.00 mg kg-1) and enzyme activity (612.42 g TPF hydrolysed µg-1 compost 24 h-1). A relative lower C:N ratio was also observed for T9 (34.77%). In part II of the study, a field experiment was conducted from December 2023 to March 2024 with the tomato variety Vellayani Vijai as the test crop. In the field, 10 treatments were applied as follows: T1 to T6 - 6 selected enriched NADEP composts, T7- Bokashi compost prepared from L. flava enriched with calcium apatite, epsom salt and sylvinite, T8- KAU POP recommendation, T9- KAU POP (organic) recommendation and T10- Absolute control. Analysis of the postharvest soil for chemical properties revealed that the highest value of organic carbon (1.13%), nitrogen (311.09 kg ha-1) and phosphorous (80.54 kg ha-1) was recorded for T7 which was on par with T4, while the highest value of available potassium was recorded for T7 (260.55 kg ha-1). T7 recorded the highest values of iron (46.50 mg kg-1), manganese (22.41 mg kg-1), zinc (4.25 mg kg-1) and copper (1.66 mg kg-1), on par with T4, which exhibited iron (45.60 mg kg-1), manganese (21.37 mg kg-1), zinc (4.12 mg kg-1) and copper (1.57 mg kg-1). The highest value of dehydrogenase activity was recorded by T7 (292.31 µg of TPF hydrolysed g-1 of soil 24 h-1) which was on par with T5 (288.91 µg of TPF hydrolysed g-1 of soil 24 h-1) and T4 (278.22 µg of TPF hydrolysed g-1 of soil 24 h-1). The boron content was found to be highest for T7 (0.69 mg kg-1). 167 Analysis of the rhizosphere soil showed that the highest value of microbial biomass carbon (84.74 mg kg⁻¹ soil) was recorded by T4, followed by T1 (83.11 mg kg-1 soil), T6 (83.11 mg kg-1 soil) and T7 (81.48 mg kg-1 soil). The soil respiration (4.02 mg CO2 g-1) and microbial respiratory quotient (49.67) were highest for T7 which was on par with T4 with soil respiration (3.98 mg CO2 g-1) and microbial respiratory quotient (46.98). Treatment T7 recorded the highest values of bacteria (7.69 log cfu g-1 soil), fungi (5.32 log cfu g-1 soil) and actinomycetes (5.15 log cfu g-1 soil) which was on par with T4. Treatment T7 recorded the highest number of fruits per plant (62.00) which was on par with T4 (60.33). Fruit girth (14.50 cm) and fruit length (4.98 cm) were highest for T4, which was on par with T1 and T7. T7 recorded the highest value for yield per plant (1.67 kg), and total yield (43.97 t ha-1), which was on par with T4 and T3. The highest B:C ratio was reported by T4. From the study, T4 (NADEP compost prepared from 1:1 mixture of L. flava and E. crassipes enriched with calcium apatite and epsom salt) were concluded as the best compost. T4 (NADEP compost prepared from 1:1 mixture of L. flava and E. crassipes enriched with calcium apatite and epsom salt) and T7 (Bokashi compost prepared from L. flava enriched with calcium apatite, epsom salt and sylvinite) recorded the highest values for majority of the available macro and micronutrients, organic carbon and enzyme activity. Considering both soil parameters, yield parameters and B:C ratio, T4 (NADEP compost prepared from 1:1 mixture of L. flava and E. crassipes enriched with calcium apatite and epsom salt) was identified as the best treatment.