Transformative Impact of Balanced Nutrition on Sustainable Crop Production and Soil Health in a 65-Year-Old Long-Term Trial in Germany

Yara’s Hanninghof long-term trial (LTT) in Duelmen, Germany, celebrated its 65th anniversary on September 5 and 6, 2023. It is one of the European 115 classical LTTs on fertiliser conducted on stationary sites for more than 50 years and is still operating. It was established in 1958 on loamy sand soil to study long-term effects of different nutrient application strategies on crop production and soil health. Potato-cereal rotation is a common crop rotation in the area. The first potato-cereal crop rotation started with the planting of potatoes on 24th April 1958, followed by sowing winter rye on 22nd October 1958 and oats sown on 22nd March 1960; this was continued until 2008. Since 2009, maize has been included in the crop rotation as a replacement for oats. The potato, winter rye, oat, and maize crops were cultivated respectively 19, 23, 17, and 6 times between 1958 and 2022. Results of the 65-year study are presented in a comparative analysis of the different fertiliser application approaches: control (without any fertiliser), farmyard manure (FYM) alone (organic nutrition), mineral fertiliser nitrogen (N) +phosphorus (P) +potassium (K) +magnesium (Mg) application as balanced nutrition, omission of one or more nutrients from balanced mineral fertiliser application, and both FYM and mineral fertiliser together as integrated nutrition. Treatments without any fertiliser, P+K alone, N without P+K+Mg, and only FYM are considered to be unbalanced nutrition regimes.

Transformative impacts of the various nutrition regimes on the sustainability of crop production are evaluated with the following indicators: yield, revenue, yield trend and stability, N use efficiency, and land and water use efficiency. The long-term effect of nutrient application strategy on soil health is evaluated by measuring trends of soil organic carbon (C), pH, nutrient content, and overall soil health index. The balanced nutrition treatments (mineral NPKMg fertiliser alone or combined with FYM) resulted in: (1) higher yield and revenue, (2) rapidly increasing yield trend with low variation, (3) increased N, land, and water use efficiencies of crops, and (4) improved C and nutrient contents of soil. The results reveal that balanced crop nutrition supports food security, economic, environment protection, resource use, and soil health aspects of sustainable agriculture. However, the unbalanced nutrition caused by the omission of nutrients and application of only FYM resulted in: (1) lower yield and revenue, (2) slowly increasing yield trend with high variation, (3) inefficient use of N and resource, and (4) low C and nutrient content of soil. The results confirm the following drawbacks of inadequate crop nutrition: unproductive and unstable yields, inefficient resource use, decline of soil health respectively implicating food insecurity and economic loss, environmental degradation and unhealthy soil. Therefore, balanced crop nutrition is key to increasing crop yield and revenue per area with low environmental footprints while preserving ecosystems and soil health.