The present study aimed to determine the effect of precipitation and fertilization (NPKCaMg) on the changes in soil organic carbon (SOC) in a long-term field experiment set up in Nyírlugos (Nyírség region, Hungary: N: 47°41' 60'' and E: 22°2' 80'') on a Haplic Luvisol with popular rotation crops. Over the 40 year period, from 1962 to 2002, SOC pool values ranged between 2.32 and 3.36 mg·kg-1. On the untreated control plots the values remained nearly constant (3.31 mg·kg-1: ±0.29 mg·kg-1 and 0.52 mg·kg-1). In the 1st 20-year period (1963-1982), there was a significant (P < 0.001) decrease (16%) on all experimental plots, which may be due to the winter half year (WHY) precipitation (228 mm), summer half year (SHY) precipitation (288 mm), the NPKCaMg fertilizer application rate (64 kg·ha-1), and the potato-rye-wheat-lupin-sunflower crop sequence. In the 2nd 20-year period (1983-2002) SOC pool values varied between 3.13 and 4.47 mg·kg-1. The 16.9% significant (P < 0.001) increase 16.9% could be attributed to the lower WHY (204 mm) precipitation, higher SHY (320 mm) precipitation, higher NPKCaMg fertilizer rate (213 kg·hat-1), and the sunflower-grass-barley-tobacco-wheat- triticale cropping system. NPKCaMg fertilization resulted in a significant (P < 0.001) decline (16.6%) in SOC in comparison to the control plots in the 1st 20-year interval, while in the 2nd 20-year period a significant (P < 0.001) rise (up to 31.9%) was registered. During the 40 experimental years the seasonal correlations (R2) among SOC (mg·kg-1), WHY and SHY precipitation (mm) ranged from 0.3343 to 0.9078 (on the P < 0.001 significance level). The correlations (R2) on the influence of NPKCaMg fertilization on SOC (mg·kg-1) and precipitation (mm) were significant (P < 0.001): the means for WHY, SHY and over the 40 years were 0.4691, 0.6171 and 0.6582, respectively. Organic carbon reserves (mg·kg-1) in soils decreased linearly as precipitation increased (from 3.22 to 7.27 mm·yr-1). In case this trend - increasing precipitation caused by climate change reduces SOC in arable soils - will continue, and is aggravated by warming temperatures and a more altering climate (as predicted by climate change forecasts), the livelihoods of many Hungarian and European farmers may be substantially altered. Thus, farmers must take into consideration the climate (WHY and SHY precipitation), fertilization (NPKCaMg), and cropping (tuber-seed-tobacco-protein-oil-forage) changeability to optimize their SOC pool, soil carbon sequestration, soil sustainability and crop management in the nearest future.
ASJC Scopus subject areas
- Agronomy and Crop Science