Effect of organic fertilizers and reduced-tillage on soil properties, crop nitrogen response and crop yield: Results of a 12-year experiment in Changins, Switzerland

Abstract

The combined effects of the nature of fertilizers (chemical and/or organic), splitting of manure inputs and tillage intensity (reduced or conventional) on soil properties, crop production and crop response to nitrogen (N) fertilization were studied in Changins, Switzerland between 1997 and 2009. Five main-treatments were tested in a split-plot design: (i) mineral fertilizer with reduced-tillage (MinRT), (ii) manure every year plus mineral fertilizer with reduced-tillage (Ma1RT), (iii) manure every year plus mineral fertilizer with conventional-tillage (Ma1CT), (iv) manure every three years plus mineral fertilizer with reduced-tillage (Ma3RT) and (v) slurry every year plus mineral fertilizer with reduced-tillage (Slu1RT). Sub-treatments included two levels of N-fertilization: an optimal dose (according to the Swiss fertilization guidelines) and a sub-fertilization (60% of the optimal dose). The soil was a Calcaric Cambisol with, in 1997, 20.5gkg−1 of soil organic matter (SOM) in the first twenty centimeters. After twelve years of experimentation, SOM contents were 19.8, 20.3, 21.3, 21.5, and 22.8gkg−1 under respectively Ma1CT, MinRT, Ma1RT, Slu1RT and Ma3RT treatments. The main-treatments do not have a significant effect on SOM contents and chemical soil properties. When N-fertilization was non-limited (optimal dose) and manure was applied, tillage intensity had not significant effect on grain yield. When N-fertilization was non-limited with reduced tillage (RT), the crops in the treatments with organic fertilizers yielded 2–13% more grains (0.2, 0.3, 0.4 and 0.5tha−1 more for respectively rapeseed, spring cereal, maize and winter wheat) than those in treatments with mineral fertilizers only. The sub-fertilization (60% of the optimal dose) decreased the grain yields by 9, 13, 15, 7 and 16%, respectively, in MinRT, Ma3RT, Ma1RT, Ma1CT, Slu1RT. In conclusion, organic fertilizers and reduced tillage provide effective means to conserve soil fertility and crop production in the studied soil, although both enhance N fertilizer needs. Splitting manure applications into lower amounts annually did not bring any benefits to soil properties or crop production.