Soil Organic-Matter in Water-Stable Aggregates Under Different Soil-Management Practices

An experiment of different management practices in a commercial vineyard, which was established in 2006 in the locality of Nitra-Dražovce, Slovakia on Rendzic Leptosol, was used to evaluate the dynamics of soil organic-matter parameters during the years 2008–2015. The following treatments were established: 1. G (grass without fertilisation as control), 2. T (tillage), 3. T+FYM (tillage + farmyard manure), 4. G+NPK3 (grass + 3^rd intensity of fertilisation for vineyards: it means 125 kg/ha N, 50 kg/ha P, 185 kg/ha K), and 5. G+NPK1 (grass + 1^st intensity of fertilisation for vineyards: it means 100 kg/ha N, 30 kg/ha P, 120 kg/ha K). The results showed that the soil-management practices in the vineyard significantly influenced the soil organic carbon in water-stable aggregates (SOC in WSA). The content of SOC in WSA_ma increased on average in the following order: T < G < G+NPK1 < G+NPK3 < T+FYM. Intensive soil cultivation in the T treatment resulted in a statistically significant build-up of SOC in WSA_ma at an average rate of 1.33, 1.18, 0.97, 1.22 and 0.76 g/kg/y across the size fractions > 5 mm, 5‒3 mm, 2–1 mm, 1–0.5 mm and 0.5–0.25 mm, respectively. The content of non-labile carbon reflected the contents of SOC in WSA. The highest labile carbon (CL) in WSA_ma, as compared to others, was found in T+FYM. Overall, application of higher NPK doses resulted in higher content of CL in WSA_ma compared with the lower applications of NPK. On the other hand, lower applications of NPK to soil increased the content of C_L in WSA_mi, as compared to G+NPK3.