Suitability of Carbon and Nitrogen Management Indices for the Evaluation of Soil Organic Matter Under Different Soil Management Practices in a Productive Vineyard

Abstract

Soil organic matter (SOM) is considered to be the most important part of the soil. C and N and their forms are most often used to evaluate SOM. In the last decades, C indices have begun to be used to assess soil quality for C changes in SOM due to the different soil management. Since C cycle is closely related to N, there is an assumption that N indices will be sensitive to N changes in SOM under the different soil management. The objective of the study was to evaluate the extent of C and N indices on C and N changes in SOM (in Rendzic Leptosol) under the different soil management practices (1. G: grass and no fertilization - as control; 2. T: tillage; 3. T+FYM: tillage + farmyard manure; 4. G+NPK3: grass + NPK 125-50-185 kg ha-1; 5. G+NPK1: grass + NPK 100-30-120 kg ha−1) in a productive vineyard (Nitra-Dražovce; Slovakia) during the period of 13 years. The results showed that the soil organic carbon (SOC) was reduced by 26% compared to G because of intensive cultivation on one hand, but on the other hand, in T + FYM treatment no significant changes in SOC over the 13 years of the experiment were observed. A higher labile carbon (CL) content was in G+NPK3 then follows: G+NPK1 > G > T+FYM > T for topsoil. In topsoil, carbon lability increased after a higher level of mineral fertilization, while in subsoil after intensive cultivation. The values of CPI for topsoil decreased in the following order: G+NPK1 > T+FYM > G+NPK3 > T. Based on CMI values, intensive C changes in the SOM due to the soil management practices were observed in T treatment. The highest accumulation of carbon and decomposable organic matter occurred in G+NPK3. Incorporation of FYM, and both rates of NPK increased values of NMI by 45, 47 and 36% respectively compared to T for topsoil. The highest values of the NPI were detected because of farmyard manure application and mineral fertilization at a higher rate for topsoil and because of intensive cultivation, as well as plowing of FYM for subsoil.

Keywords

• vineyard
• soil organic matter
• carbon indexes
• nitrogen indexes