Hot-water extractable C and N as indicators for 4p1000 goals in a temperate-climate long-term field experiment: A case study from Hungary

Soil organic matter (SOM) consists of various labile and stable fractions, which are differently influenced by agricultural activities land-use change. This study, aimed at investigating the feasibility achieving 4p1000 goals on conventionally tilled plough-land, was carried out in a 42 years-old long-term field experiment (LTE), effect three farmyard manure (FYM) doses FYM equivalent NPK mineral fertiliser rates can be examined, together with that without ploughed-in plant residues. The soil total carbon (SOC) nitrogen (SN) hot-water soluble C (HWC) N (HWN) fractions were determined (0–0.3 m) used as indicators. parameters area compared those grassland similar characteristics. suitability these for use quality indicators (SQI) also examined terms fertility. results showed most sensitive fraction detection treatment effects HWC HWN. Increases significantly related to gains SOC stocks. Based close correlation between factors both crop yield it is recommended they should prediction changes studies fertility or quality. initial stock 40.46 Mg ha?1 became 40.27–47.05 after four decades, while rose 69.31 ha?1. sequestration rate (CSR) fertilisation systems exhibited following order: residue incorporation >FYM addition > (0.147–0.156, 0.101–148 –0.021–0.065 yr?1, respectively), an outstandingly high value 0.687 yr?1 recorded grassland. Despite fact potential (CSP) remained (55.36–62.48%), achievement 4 per 1000 aims only ensured treatments involving short term.