Soil biochemical properties in a semiarid Mediterranean agroecosystem as affected by long-term tillage and N fertilization

Abstract

Tillage and N fertilization practices contribute to the balance between soil C inputs and outputs. Thus, the impacts of both practices and their interactions on soil organic C (SOC) dynamics must be studied. The main objective of this study was to determine long-term effects of tillage and N fertilization on soil biochemical properties in a longterm experiment established in 1996 on a dryland Typic Xerofluvent soil cropped with barley (Hordeum vulgare L.) in NE Spain. The response of SOC concentration, soil microbial biomass carbon (SMBC) and soil enzyme activities (DHA, dehydrogenase, and PRA, protease) to different tillage (no-tillage, NT; reduced tillage, RT; and conventional tillage, CT) and N treatments (zero, 0 kg N ha-1 ; medium, 60 kg N ha-1 ; and high, 120 kg N ha-1) were measured in 2008 at four soil depths (i.e., 0-5, 5-10, 10-25 and 25-50 cm). All the soil biochemical properties studied showed significant differences for tillage, depth and the interaction between tillage and soil depth. However, N fertilization rates only affected the SMBC content, which was greater under 120 kg N ha-1 than under 0 kg N ha-1 in the 10-25 cm soil layer. In the soil surface layer (0-5 cm), SOC, SMBC and DHA levels in CT were about 50% of the levels in the NT plots. However, in the 10-25 cm soil layer, a greater SOC concentration in CT compared with NT and RT was also accompanied by SMBC and DHA values 30% higher in CT. Below 25 cm soil depth, similar values of soil biochemical properties were found among tillage systems. There was a significant correlation among almost all the parameters studied, with the greatest correlations between SOC and SMBC and between SOC and DHA. In semiarid Mediterranean conditions, after twelve years of experiment, tillage impacted soil biochemical properties in a greater extent compared with N fertilization even though this effect was only limited to the upper soil layers.

Effect of straw returning on soil organic carbon in rice–wheat rotation system: A review

“…The C/N ratio is an important factor affecting the decomposition of crop straw (Trinsoutrot et al, 2002). For every 100 g of straw decomposed by microorganisms, approximately 0.8 g of nitrogen is required (Henriksen & Breland, 2002), and the appropriate C/N ratio for soil microorganisms to decompose organic materials is approximately 25-30:1; while the C/N ratio of straw of Gramineae crops is generally higher than this value (Kochsick & Knops, 2013), the microbial decomposition of returned rice straw and wheat straw requires the original nitrogen in the soil, which leads to competition between microorganisms and crops for nutrients and reduces the decomposition rate of returned straw (Álvaro-Fuentes et al, 2013). In addition, straw has more soluble organic matter and a higher C/N ratio in the early stage of decomposition, and as it decomposes, the soluble matter and the C/N ratio gradually decrease.…”

Agricultural insurance policies in Spain and the EU: an analysis of existent and new risk management tools focusing on indirect risk assessment, and asymmetric information

“…For example, with respect to the assumptions that have to be made on the horizontal heterogeneity of the soils, the effect of tillage, or the criterion used to fix the parameters for permanent wilting point (PWP) and field capacity (FC) required in soil modules. Tillage alters soil structure and soil organic matter content (Álvaro-Fuentes et al, 2013;Plaza-Bonilla et al, 2014;White et al, 2009); consequently, it modifies soil water dynamics. Observed data used within this work shows differences in soil water content between the two tillage treatments, being higher in plots with no tillage than in those with minimum tillage, especially in deeper layers (θ 25-50cm ) ( Figure 5).…”

Yield gap associated with crop management in wheat (Case study: Ardabil province-Parsabad Moghan)

“…Early planting, suitable farm management (Anderson, 2010), results in reducing the number of operations for providing land, improved physical and chemical properties (Arvidsson et al, 2014 andRomaneckas et al, 2012) of soil (Morris et al, 2010) and biological properties (Melero et al, 2009 andMorris et al, 2010), environmental regulations and maintaining the optimum rate of nitrogen (Carver, 2010). Besides improving soil structure, air and water infiltration and biological and microbial activities (Soane et al, 2012), reduces mineralization and increase soil organic carbon in the long term which has impact on the activity of soil microbial biomass (Alvaro-Fuentes et al, 2013;Melero et al, 2009;Swedrzynska et al, 2013 andCarver, 2010).…”