LAUSR

Poor subsoil properties are difficult to ameliorate and detrimental to soil fertility and crop yield. The effects of loosening (L) and loosening + straw (LS) ∼60 Mg ha-1 into the subsoil (25-40 cm depth) on crop yield, water flow and the nitrogen balance components under bare soil conditions and a barley crop were investigated in an about 21-month lysimeter study and compared with a control (C) treatment. Undisturbed soil columns (n = 12) were excavated from an agricultural field in May 2016, installed at a lysimeter station and exposed to outdoor climatic conditions in Uppsala, Sweden, in August 2016. Spring barley (Hordeum vulgare L. cv. Makof) was grown between June and September 2017. Total nitrogen (N) leaching loads over the 21-month were high (74-193 kg ha-1 ). The LS treatment reduced the N load by 49% (P = 0.01) and 62% (P = 0.001) compared with the L treatment and C, respectively. Loosening reduced N load by 25% (P<0.07) compared to the control. Emissions of N2 O were low (0.04-0.07 kg N ha-1 ) and no differences were observed between treatments. Leaf relative chlorophyll content was lower in the LS treatment than L and C (P<0.05). Yield was also lowest in the LS treatment (5.8 Mg ha-1 ), 7% and 8.5% lower than in the C and L treatments (P>0.05), respectively. These results suggest that LS can reduce N leaching and possibly water flow. The overall effects of LS on crop performance and N removal and leaching should be further scrutinised in long-term field studies. This article is protected by copyright. All rights reserved.