Conservation Agriculture Research Updates - June 2024

This paper provides an overview of tillage in Hungary. Interestingly, they say interest in CA dates back 120 years, although significant changes did not occur until the last 50 years. Progress was driven by the need to protect soil, the opportunity to raise farming standards, and the need to mitigate climate-related threats. Since the average yield in Hungary was usually sufficient for the domestic need, the main objective of crop production was to avoid yield loss. This study utilized long-term experimental data and monitoring results. The experiences and first results in no-till and strip-tillage showed that difficulties can be reduced by identifying site-specific technology solutions. They suggest that the need for subsoiling is not a matter of debate nowadays but rather the timing of operation and the investigation of the duration of the effects. The area of plowed soils has decreased recently, but improved implementation by farmers is required.

This paper from New Zealand looked at various tillage options with and without irrigation on SOC, fungal biomass and their relation to to soil aggregate sizes in a 14-year experiment. They hypothesized that long-term irrigation and intensive tillage would negatively affect soil aggregation. The experiment was started in 2003 and data taken in 2017. Two tillage treatments were intensive tillage (IT) to 20-25cm compared with no-till (direct drill - DD) and irrigation was sprinkler and none (rainfed). Soil samples (0-5 cm layer) were analyzed for pore size distribution, specific surface area and microbial biomass. Sieving was also used to separate macro- (LM) and micro-aggregates (SM), particle sized silt + clay and fine particles. Both DD and rainfed management increased total SOC content of the bulk soil. The LM and its SOC increased in DD compared to IT. A higher fungal:bacteria (F:B) ratio was generally accompanied by a greater LM fraction and mean weight aggregate diameter, highlighting the importance of fungi in the formation of LM. They concluded that detrimental effects on soil aggregation by tillage and irrigation was not conclusive and a longer study period is needed to confirm.

This study looked at different tillage systems (NT vs moldboard (CT)) with 4 fertilizer regimes (None (CON), NPK (MIN), Compost (ORG), & NPK + Compost (MIX) on SOC and microbial biomass 20 years later. The abundance of the microbial community and N-functional guilds within the soil profile (up to a depth of 60 cm) was also determined. SOC was higher in NT than CT at 0-10 cm depth. Organic fertilization increased SOC in both tillage treatments to 20cm. Microbial biomass decreased with depth due to a decrease in SOC, and, consequently, were higher in NT than in CT, in the top 20 cm soil for microbial biomass and bacterial abundance and top 10 cm for fungi and archaea. They conclude that their study provided  insights that can aid in development of effective strategies for steering soil microbiome responsible for N2O emissions.