Effects of input level and crop diversity on soil nitrate-N, extractable P, aggregation, organic C and N, and nutrient balance in the Canadian Prairie

Abstract

A field experiment was conducted from 1995 to 2006 on a Dark Brown Chernozem (Typic Boroll) loam soil at Scott, Saskatchewan, Canada to determine the influence of input level and crop diversity on accumulation and distribution of nitrate-N and extractable P in the soil profile, and soil pH, dry aggregation, organic C and N, and nutrient balance sheets in the second 6-year rotation cycle (2001)(2002)(2003)(2004)(2005)(2006). Treatments were combinations of three input levels (organic input under conventional tillage-ORG; reduced input under no-till-RED; and high input under conventional tillage-HIGH), three crop diversities (fallow-based rotations with low crop diversity-LOW; diversified rotations using annual cereal, oilseed and pulse grain crops-DAG; and diversified rotations using annual grain and perennial forage crops-DAP), and six crop phases including green manure (GM), chem-fallow or tilled-fallow (F). Amount of nitrate-N in 0-240 cm soil was usually highest under the HIGH input-LOW crop diversity treatment and lowest under the ORG input-DAP crop diversity treatment. The distribution of nitrate-N in various soil depths suggested downward movement of nitrate-N up to 240 cm depth, especially with LOW crop diversity compared to DAP crop diversity, and with HIGH input. In some years, the ORG input systems had higher nitrate-N than the RED or HIGH input systems, which was attributed to low extractable P in soil for optimum crop growth and reduced nutrient uptake with ORG input management. Extractable P in soil was higher by a small margin for HIGH or RED input relative to ORG input in the 0-15 cm layer, suggesting little downward movement of P. Crop diversity did not affect extractable soil P due to the low baseline levels of P in this soil. The proportion of fine dry aggregates (\1.3 mm, erodible fraction) in 0-5 cm soil was highest with LOW crop diversity-HIGH input system, and lowest with DAG diversity-RED input system. The opposite was true for large aggregates ([12.7 mm). Wet aggregate stability was higher for RED input compared to ORG and HIGH input, which was attributed to the increase in the concentration of organic C in aggregates in the RED input system. Amount of light fraction organic

Review: Redesigning Canadian prairie cropping systems for profitability, sustainability, and resilience

“…They also have reduced potential for nitrate leaching (Malhi et al 2009) and tend to be more efficient in their energy use and produce lower levels of GHG emissions (Zentner et al 2011b). Including legumes in rotation may have a relatively large impact on GHG emissions and energy use due to biological nitrogen (N) fixation (BNF) and the accompanying reduction in N fertilizer requirements (Asgedom and Kebreab 2011).…”

“…Their deep root systems are able to retrieve nutrients from subsoil, thus reducing nitrate leaching, and can sequester C deep in the profile Olmstead and Brummer 2008;Malhi et al 2009). Perennial forages also provide habitat for wildlife, in particular nesting birds and pollinators (Jefferson et al 1999;Carvell et al 2006;Arnold et al 2007).…”

“…Positive effects of no-till on soil health parameters have been widely documented and include major reductions in soil erosion and fuel consumption, reduced CO 2 emissions, and enhanced water quality, biological activity, soil fertility and production stability (Pretty 2008;Derpsch et al 2010;Lafond et al 2011 and references therein). Studies in the NGP have also reported better soil aggregation, enhanced soil organic C, and increased potentially mineralizable N in no-till soils (McConkey et al 2003;Liebig et al 2004;Pikul et al 2009;Malhi et al 2009;Lafond et al 2011). Microbial biomass, especially of mycorrhizal fungi, is often, but not always, greater in no-till soils (Liebig et al 2004;Helgason et al 2010;Monreal et al 2011); soil organism community structure may also be different in no-till than tilled soils (Helgason et al 2010).…”

Temporal Variations in Diazotrophic Communities and nifH Transcripts Level Across the Agricultural and Fallow Land at Jaipur, Rajasthan, India

“…Amount of mineral nitrogen forms like ammonium and nitrate in soil depends on the amount of humus, C:N ratio, fertilizers and climatic conditions. So these forms of nitrogen content varied greatly between the years and within the year [19]. Application of fertilizers in summer increases the soil nitrate and ammonium content [20].…”

The Sustainability of Organic Grain Production on the Canadian Prairies—A Review

“…They also reported higher N uptake with alfalfa mulch treatments than with synthetic fertilizers in the wheat and second-year oat crop, and the oat crop also had a higher grain yield. Malhi et al [34] reported that organic cropping systems employing some form of fallow, or green manure partial-fallow, tend to accumulate more nitrate-N in the rooting zone than high input systems. They further suggested that fallow systems employing a green manure limited leaching because they temporarily stored available nitrate-N, while using soil water that could drive leaching, compared with fallow that excluded vegetation.…”