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
Highlights
► Reduced-tillage was as effective as 12 t ha−1 y−1 of manure in conserving soil organic matter. ► Effects of organic fertilizers and reduced-tillage on chemical soil properties were not significant. ► Organic compared to mineral fertilizer improved potential yields. ► Reduced compared to conventional tillage, did not show any significant effect on potential yields.
Introduction
The use of organic fertilizers is considered to be an effective way of increasing soil organic carbon (SOC) sequestration and supplying micronutrients to crops in comparison with the use of mineral fertilizers only (Lal, 2009). Long term cultivation without organic fertilizers usually leads to a decrease in SOC and total N contents (Dick, 1992) and in crop yield (Bhandari et al., 2002, Regmi et al., 2002). However, with the increased accessibility to chemical fertilizers and farm specialization, the use of organic fertilizers has declined dramatically in some regions of Switzerland over the last decades. This raises the question of the maintenance of soil organic matter (SOM) content on farms without livestock (Vullioud et al., 2006).
SOM is a key component of the agrosystem as it prevents soil degradation, reduces the risk of water pollution and enhances chemical, biological and physical soil properties (Swift, 2001). Consequently, improvement in the SOM content generally leads to an increase in agronomic productivity through a better use of energy-based inputs (e.g., fertilizers, water, pesticides) (Lal, 2011). Changes in the SOM content may also alter the potential of soil to supply or sequester nutrients, especially N, through changes in mineralization–immobilization turnover (Jansson and Persson, 1982) and cation exchangeable capacity (Lal, 2006).
The build-up of SOC is a slow process depending on the amount of carbon (C) input to soil as crop residue, and its balance with SOM decomposition (Nyborg et al., 1995). Cropping systems affect SOC levels because of their effects on C inputs and C losses (Follett, 2001). In general, application of organic fertilizers and especially manure, either alone or in combination with mineral fertilizers, increases SOC content (Blair et al., 2006, Gong et al., 2009, Maltas et al., 2012, Manna et al., 2007, Rudrappa et al., 2006;). In contrast, inorganic fertilizers often produce contradictory effects on SOC content (Ghani et al., 2003, Gong et al., 2009, Simon, 2008). This uncertainty is partly attributed to the specific processes governing C sequestration under agronomic practices, varying with soil type, climate and crop rotation. No-till (NT) is generally known to improve SOM content (Bayer et al., 2006, Bernoux et al., 2006, Campbell et al., 1999, Follett, 2001, Franzluebbers, 2005, Lal et al., 1998, Lal, 2009, Six et al., 2002, Tebrügge and Düring, 1999, West and Post, 2002), especially in the plowed soil layer (Baker et al., 2007, Ogle et al., 2005, Puget and Lal, 2004), because of changes in soil structure and lower decomposition rates due to physical protection of C within aggregates (Jastrow et al., 1996, Six et al., 2000). However, other studies questioned whether NT actually increases SOC content (Angers et al., 1993, Angers et al., 1997, Anken et al., 2004, Baker et al., 2007, Christopher et al., 2009, Franzluebbers and Arshad, 1996, Wright et al., 2005). The storage capacity of SOM in these systems varies widely depending on soil characteristics (texture, slope), climatic conditions, initial SOM content, differences in C inputs from crop production and C decomposition in the soil and management practices (Balesdent et al., 2000, Collins et al., 2000, Doran and Smith, 1987, Paustian et al., 1997). Numerous studies have also shown that NT can increase or decrease crop yields (Al-Kaisi et al., 2005, Beyaert et al., 2002, Dam et al., 2005, Drury et al., 2003, Griffith et al., 1988, Halvorson et al., 1999, Hammel, 1995, Hussain et al., 1999, Potter et al., 1996, Tarkalson et al., 2006, Wilhelm and Wortmann, 2004) depending on environmental conditions and have varying impact on C inputs to soil (Ogle et al., 2012).
Since long-term effects of agricultural management practices vary greatly among sites conditions, it is necessary to evaluate these effects under different soil–climatic conditions (Johnston, 1997, Mitchell et al., 1991). The objective of the present study was to quantify, for a Cambisol and under the relatively dry climate of western Switzerland, the medium-term effect (12 years) of organic fertilization and reduced-tillage practices on soil properties, crop yield and crop response to N fertilization. The questions addressed were: (i) how the nature of organic fertilizers, the splitting of manure application and the tillage intensity affect SOM content, and (ii) what are the consequent effects of these practices on soil chemical properties, crop N response and crop yield.
Section snippets
Site description and experimental design
A field experiment was established in 1997 by the Swiss Research Station Agroscope ACW (46°24′E, 06°13′N; altitude: 445 m) on a Calcaric Cambisol with 230 g kg−1 of clay and 410 g kg−1 of silt in the twenty uppers centimeters of soil. Mean annual rainfall and temperature were, respectively, 954 mm and 10 °C (means from the last 30 years). Before starting the experiment, the area was covered with spring barley. Some selected physico-chemical characteristics are presented in Table 1.
The experimental
Organic soil properties
On the N100 sub-treatments of the five main-treatments, SOM contents in 2009 (Table 4) were not significantly (P < 0.05) different compared to SOM contents in 1997 (Table 1). Thus under conditions of the present study, the application of 12 t ha−1 of manure every year (Ma1CT) was sufficient to maintain SOM content when the soil was conventionally-ploughed. When only mineral fertilizers were used (MinRT), the reduced tillage (RT) seems to be also effective to conserve SOM content. Nevertheless, it
Conclusion
In order to maintain the sustainability of cropping systems, preventing the decrease of SOM content is a key factor. Under the conditions of the present study, the application of 12 t ha−1 y−1 of manure seems to be an effective way to conserve SOM content when the soil was conventionally ploughed (Ma1CT) or reduced-tillage and mineral fertilizers were used (MinRT). Twelve years of experimentation were not long enough to show significant effects of organic fertilizers and reduced-tillage on SOM
Acknowledgment
This work was funded by the Research Station Agroscope Changins-Wädenswil.
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