Conservation tillage as a dual-benefit strategy: substantial reductions in sediment and nutrient export with limited maize yield penalties

Soil erosion and nutrient losses threaten soil health, water quality, and the long-term sustainability of agroecosystems. Degradation risks are highly pronounced in croplands on sloped soils with naturally poor characteristics, managed conventionally, where intense rainfall events lead to high erosion rates. Despite promotion of conservation practices, research linking event-scale runoff and sediment dynamics to specific tillage methods and crop yield outcomes remains scarce for many South-East European agricultural systems.

An experiment was established in 2024 to monitor hydrological and erosional responses in a maize cultivation on sloped Stagnosols in continental Croatia. Four tillage management were evaluated: conventional ploughing, subsoiling, chisel tillage, and no-tillage. Twelve experimental plots (100 m long, 8 m wide) were set up, containing overland flow collectors. During six rainfall–runoff events, from May to October, runoff, sediment concentration, soil loss, and losses of carbon, nitrogen, and phosphorus were determined. Soil bulk density and penetration resistance were assessed at 0–10 and 10–30 cm depth during spring and autumn, while maize grain yield was recorded to assess the impact of soil conservation strategies on productivity.

Ploughing resulted in significantly greater degradation compared to all other tillage management systems. Relative to ploughing, soil loss decreased by 83% with subsoiling and 77% with chisel tillage, while no-tillage achieved a 94% reduction. Phosphorus and nitrogen losses exhibited similar trends, with reductions of 83% and 82% under subsoiling, 78% and 76% under chisel tillage, and 90% and 88% under no-tillage, respectively. Carbon loss was also substantially reduced, ranging from 76% (chisel tillage) to 89% (no-tillage). Runoff was reduced by 27–43%, suggesting that conservation tillage primarily limited soil detachment and transport rather than completely preventing runoff. Erosion patterns were highly variable, with two rainstorms accounting for approximately 67% of total soil loss under conventional ploughing.

Soil physical properties were consistent with observed hydrological patterns. At the 0–10 cm depth, bulk density was lowest under chisel tillage and subsoiling (approximately 1.37 g cm⁻³) compared to ploughing (1.42 g cm⁻³). Penetration resistance was highest under no-tillage (1.41 MPa) and lowest under subsoiling (0.57 MPa). At the 10–30 cm depth, no-tillage exhibited the highest bulk density (1.48 g cm⁻³) and penetration resistance (2.10 MPa), indicating greater mechanical impedance that may contribute to the observed yield trade-off. Chisel tillage and subsoiling maintained yields relative to ploughing (+2.0% and −0.7%, respectively), whereas no-tillage reduced yield by 17.6%, indicating that a no-tillage system very likely may require additional residue, nutrient, and weed management strategies.

The present study shows that conservation tillage involving loosening (chisel and subsoiling) can provide immediate reductions in sediment and nutrient losses with no significant yield loss in maize cultivation systems.

Keywords: Soil erosion, conservation tillage, sustainable agriculture, sediment transport, environmental impact, FORMclimaSOIL

Acknowledgement: This work was supported by the Croatian Science Foundation through the project “Forming climate smart soils: Mitigation of soil erosion and degradation processes in Croatian agricultural systems” (IP-2022-10-5692) (FORMclimaSOIL).