Time-dependent release of some plant nutrients from different organic amendments in a laboratory study

Abstract

Purpose

Soil fertility management requires a precise assessment of nutrient release from organic amendments to decide the rates and frequency of application.

Methods

Time-dependent release of some macro- and micro-nutrients from farmyard manure, mushroom compost, poultry manure, vermi-compost, biogas slurry and biochar of Lantana sp. was studied during 120 days incubation through entrapment of released nutrients on ion exchange resins.

Results

Highest total concentration of K, Ca, Mg and S was in farmyard manure, Fe and Mn in mushroom compost, P, Zn and Cu in biogas slurry and B in biochar. Farmyard manure had the highest C:N ratio (34.2), while other organic amendment had C:N ratio < 20. The highest release of P, Ca, Mg, Zn and Cu was recorded from biogas slurry, of K and S from farmyard manure, of B from poultry manure and of Fe and Mn from mushroom compost. Mean percentage of total nutrient released was 30.5% P, 71.8% K, 23.1% Ca, 24.4% Mg, 29.3% S, 47.2% Zn, 22.9% Cu, 38.6% Fe, 46.6% Mn, and 70.9% B. Nutrient release from different organic amendments conformed to zero-order kinetics. The percent of total released nutrient, release kinetic constants and half-life of nutrients was related to the properties of organic amendments.

Conclusions

Based on the released amount of nutrients from different organic amendments, the best source seemed to be farmyard manure for S and K, mushroom compost for Fe and Mn, biogas slurry for P, Ca, Mg, Zn and Cu and poultry manure for B.