Strip-Till Combined with Slurry Band Injection Below Maize Seeds—A New Approach to Enhance the Nitrogen Efficiency of Organic Fertilizers

Abstract

The slurry strip-till (STR) technique combines reduced tillage (strip tillage) with the precise injection of slurry below the plant seed position. This technique is designed to improve the nitrogen (N) use efficiency of organic fertilizers. The present study aimed at evaluating how efficiently the strip-till technique uses N compared to the conventional broadcast slurry application (CONV) in the case of maize (Zea mays L.). Field trials with five treatments (unfertilized control, slurry strip-till with and without nitrification inhibitors (NIs), conventional surface broadcast slurry incorporation with and without NI) were conducted on loamy sandy soils in northern and central Germany for three study years (2014–2016). The soil mineral N (SMN) contents were analyzed at three depths (0–30, 30–60, 60–90 cm) to ascertain the N displacement out of the topsoil. Furthermore, maize dry matter (DM) yields and N uptakes were determined to calculate the N recovery efficiency (NRE) of the studied application systems.SMN analyses showed an increased proportion (+60%) of ammonium nitrogen (NH4-N) in SMN after the addition of NI until 34 to 40 days after fertilization. Nevertheless, the DM yields and N uptakes of STR treatments were not significantly different from CONV-treated plots. The addition of NI did not lead to significantly increased DM yields and N uptakes. This was most probably due to negligible nitrate leaching in the early growth stages. The STR treatments (STR and STR + NI) showed the highest N recovery efficiencies (up to 78%) among all treatments indicating the lowest potential N losses of this application system. Significant differences between STR and CONV treatments were found only in 2014 and partially in 2015, however. Thus, it can be assumed that the STR system is beneficial to enhance the N efficiency of the slurry application, although further research is required to prove this.KeywordsAmmonium depotBroadcast applicationNitrate leachingNitrification inhibitorStrip tillage