Long-term tillage, straw management and N fertilization effects on quantity and quality of organic C and N in a Black Chernozem soil

Abstract

Soil, crop and fertilizer management practices may affect the amount and quality of organic C and N in soil. A long-term field experiment (growing barley, wheat, or canola) was conducted on a Black Chernozem (Albic Argicryoll) loam at Ellerslie, Alberta, Canada, to determine the influence of 19 (1980 to 1998) or 27 years (1980 to 2006) of tillage (zero tillage [ZT] and conventional tillage [CT]), straw management (straw removed [S Rem ]and straw retained [S Ret ]) and N fertilizer rate (0, 50 and 100 kg N ha -1 in S Ret and 0 kg N ha -1 in S Rem plots) on total organic C (TOC) and N (TON), and light fraction organic C (LFOC) and N (LFON) in the 0-7.5 and 7.5-15 cm or 0-5, 5-10 and 10-15 cm soil layers. The mass of TOC and TON in soil was usually higher in S Ret than in S Rem treatment (by 3.44 Mg C ha -1 for TOC and 0.248 Mg N ha -1 for TON after 27 years), but there was little effect of tillage and N fertilization on these parameters. The mass of LFOC and LFON in soil tended to increase with S Ret (by 285 kg C ha -1 for LFOC and 12.6 kg N ha -1 for LFON with annual rate of 100 kg N ha -1 for 27 years) , increased with N fertilizer application (by 517 kg C ha -1 for LFOC and 36.0 kg N ha -1 for LFON after 27 years), but was usually higher under CT than ZT (by 451 kg C ha -1 for LFOC and 25.3 kg N ha -1 for LFON after 27 years). Correlations between soil organic C or N fractions were highly significant in most cases. Linear regressions between crop residue C input and soil organic C or N were significant in most cases. The effects of tillage, straw management and N fertilizer on soil were more pronounced for LFOC and LFON than TOC and TON, and also in the surface layers than in the deeper layers. Tillage and straw management had little or no effect on C:N ratios, but the C:N ratios in light organic fractions significantly decreased with increasing N rate (from 20.06 at zero-N to 18.91 at 100 kg N ha -1 ). Compared to the 1979 results, in treatments that did not receive N fertilizer (CTS Rem 0, CTS Ret 0, ZTS Rem 0 and ZTS Ret 0), CTS Rem 0 resulted in a net decrease in TOC concentration (by 1.9 g C kg -1 ) in the 0-15 cm soil layer in 2007 (after 27 years), with little or no change in the CTS Ret 0 and ZTS Rem 0 treatments, while there was a net increase in TOC concentration (by 1.2 g C kg -1 ) in the ZTS Ret 0 treatment. Straw retention and N fertilizer application at 50 and 100 kg N ha -1 rates showed a net positive effect on TOC concentration under both ZT (ZTS Ret 50 by 2.3 g C kg -1 and ZTS Ret 100 by 3.1 g C kg -1 ) and CT (CTS Ret 50 by 3.5 g C kg -1 and CTS Ret 100 by 1.6 g C kg -1 ) treatments in 2007 compared to 1979 data. In conclusion, the findings suggest that retention of straw, application of N fertilizer and elimination of tillage would improve soil quality, and this might increase the potential for N supplying power of the soil and sustainability of crop productivity.

Short-term residual effects of various amendments on organic C and N, and available nutrients in soil under organic crop production

“…Inorganic amendments usually supply specific nutrients and do not contribute directly to soil organic matter, resulting in much less contribution to soil organic C and N. Other recent research in Germany has also shown significant increase in soil organic matter after four annual applications of farm yard manure (FYM) to organic crops [7]. The relative greater increases in C or N for LFOC or LFON than TOC or TON in our study are in agreement with other research, where light organic fraction was also more responsive to management practices than total organic fraction [14][15][16]. The greater build-up of light organic fraction at Star City than Spalding was probably due to the differences in soil type (Gray Luvisol soil at Star City versus Dark brown Chernozem at Spalding) and climatic conditions (relatively warmer temperature at Spalding than Star City) at the two sites.…”

“…Soil quality is linked to organic matter (or organic C) in soil, and the increase of organic C in soil is a function of the amount of C input to soil and its balance with decomposition [14][15][16]. Thus, organic amendments (because of both direct and indirect C input) can have much greater residual benefits in improving soil organic matter/quality and fertility compared to inorganic amendments which contribute only indirectly to C input in soil [3][4][5][6][17][18][19].…”

Conservation Agriculture and Soil Quality– An Overview

“…Moreover, the chelating of these nutrients with organic matter in non-disturbed soil leads the improvement of soil nutrient status in different soil depths (Borie et al, 2006;Singh et al, 2014) and thus causes enhancement of soil NPK status. The similar findings of enhancement in available nutrients due to CA practices in soil were also reported by Graham et al, 2002;Borie et al, 2006 andWang et al, 2008 for N;Malhi et al, 2011for P and Du Preez et al, 2001and Govaerts et al, 2007 for K. The enhancement in available NPK status due to ZT and PB practices was also reported by Parihar et al, 2011. Most research reported that tillage practices does not affect extractable Ca and Mg levels of soil (Govaerts et al, 2007;Duiker and Beegle, 2006) primerily in the condition where CEC is associated with clay particles (Duiker and Beegle, 2006).…”

Effects of straw mulching on water consumption characteristics and yield of different types of summer maize plants

“…Hence, the essence of efficient water use was root and shoot equilibrium (Gao et al 2007). Straw mulching affects not only the soil moisture content but also soil temperature and soil nutrient accumulation and distribution (Yan et al 2007, Li et al 2008, Malhi et al 2011. Therefore, to understand the water consumption characteristics of summer maize with straw mulching more clearly, the regulation and control mechanisms of root and shoot equilibrium, as well as its interaction mechanisms under different soil and water conditions should be studied.…”