The effect of tillage intensity on soil structure and winter wheat root/shoot growth

Abstract

Despite a vast amount of data on the effect of tillage on crop productivity, surprisingly there is little detailed information available on the influence on below and aboveground crop growth dynamics. Such information is essential for developing sustainable cropping systems. The objective of this study was to investigate the effect of tillage intensity on crop growth dynamics and soil structure. A tillage experiment was established in autumn 2002 on two Danish sandy loams (Foulum and Flakkebjerg) in a cereal‐based crop rotation. The tillage systems included in this study were direct drilling (D), harrowing 8–10 cm (H8‐10), and ploughing (P). A single‐disc drill was used in the H8‐10 and D treatments and a traditional seed drill in the P treatment. Measurements were carried out in 2004–05 and 2005–06 and winter wheat was grown in both years (first and second year winter wheat). Shoot and root growth was followed during the growing seasons using spectral reflectance and mini‐rhizotron measurements, respectively. A range of soil physical properties were measured. We found decreased early season shoot and root growth with decreasing tillage intensity. Differences diminished later in the growing season, although significant treatment effects were observed throughout the growing season for the second year winter wheat. The formerly ploughed layer in the D and H8‐10 treatments was noticeably compacted as indicated by increases in both penetration resistance and bulk density. Nitrate leaching increased with decreasing tillage intensity for the first year winter wheat at Foulum. In general ploughing resulted in the highest grain yields. This study highlights the important interaction between soil structure and crop growth dynamics.

Belowground carbon input and translocation potential of fodder radish cover-crop

“…In this study, we also observed significantly higher average soil bulk density in DD (1.46) relative to CT (1.42), which implies a higher penetration resistance in DD than in the CT plots. Similarly, Munkholm et al (2008) observed a higher root penetration resistance and low oxygen availability in DD relative to CT plots in our present a Relative distribution (%) between soil depths within specific pools; for each treatment column value followed by different letters are significantly different P<0.05; R = roots, S = soil trial. This implies that our DD plots are subject to soil compaction, root penetration resistance and low oxygen availability, which are important factors for root proliferation in the soil profile.…”

“…The main experiment was established in Autumn 2002 and has been subject of a number of earlier studies (Chatskikh and Olesen 2007;Munkholm et al 2008;Mutegi et al 2010). The experiment had a split-plot design with four replicate blocks, each with crop rotation as main treatment and tillage treatments in subplots .…”

“…Foulum soil is a Mollic Luvisol (Krogh and Greve, 1999), with 9% clay, 13% silt (2-20 μm), 44% fine sand (20-200 μm), 31% coarse sand (200-2000 μm) and 18 g C kg −1 in the top 0-25 cm soil layer (Munkholm et al 2008;Hansen et al 2010). The region has an average annual rainfall of 704 mm and long-term average temperature that varies between 0°C in January and 16°C in August (Statistics Denmark 2009) with an annual average of 7.3°C (Statistics Denmark 2009).…”

“…However, there is no empirical data to validate such suggestions that can also be used for modelling tillage C sequestration scenarios when catch-crops are part of the cropping cycle. While a number of studies have shown that increased soil compaction could impede root growth and hence reduce both below and aboveground biomass yield under no-till for a number of crops (Cannell 1985;Munkholm et al 2008), the ability of fodder radish to withstand soil compaction has also been demonstrated (Chen and Weil 2010).…”

Soil compaction resulting from different soil tillage systems

“…The increase in Pc with depth without significant BD modification suggested an increased number of contact points per unit volume resulting from the agglomeration of fine particles under the long-term action of mechanical loads, climatic agents, biological organisms and/or clay minerals acting as cementing agents, especially in RT18 (Guérif, 1994). This process could be responsible for negative effects on root growth and root-induced parameters, leading to more superficial root lateral development sometimes observed in RT (Munkholm et al, 2008;Dal Ferro et al, 2014). In the topsoil in RT18, r max and PSD max were the lowest among the layers considered.…”