Relative effectiveness of organic and inorganic nutrient sources in improving yield, seed quality and nutrient uptake of canola

The proper use of organic and inorganic nutrient sources is important to sustain high levels of crop production, while maintaining or enhancing soil and environmental quality. A 4-year (2009 to 2012) field experiment was established in spring 2009 on a Gray Luvisol (Typic Haplocryalf) loam soil at Star City, Saskatchewan, Canada, to determine the effectiveness of organic/biological (compost, wood ash [fine and granular], alfalfa pellets, distiller grain, thin stillage, glycerol, fish food additive, Penicillium bilaiae), inorganic/mineral (granular-gypsum, rapid release elemental S [RRES], rock phosphate [granular and fine]) and chemical/synthetic (granular-ammonium nitrate, triple super phosphate and potassium sulphate) nutrient sources (amendments/chemicals) in improving seed yield, straw yield, seed quality and nutrient uptake (N, P, K and S) in seed + straw of canola. Combined application of N, P and S chemical fertilizers (NPS) produced considerably greater seed yield, straw yield and nutrient uptake of canola compared to the unamended control in all four years. In treatments receiving only organic amendments, thin stillage produced the greatest seed yield, straw yield and nutrient uptake in all years, and it was similar to the NPS balanced fertilizer treatment, while fish food additive and distiller grain dry of wheat in 2009, 2011 and 2012, distiller grain dry of corn in 2009 and 2012, and compost and alfalfa pellets in 2011 and 2012 produced significantly greater seed yield, straw yield and nutrient uptake, when compared to the control. In treatments where chemical fertilizers were also applied, in addition to organic amendments, ap- plication of N fertilizer increased seed yield, straw yield and nutrient uptake substantially when combined with wood ash fine in 2009, 2010, 2011 and 2012, wood ash granular in 2009, 2011 and 2012, and glycerol in 2009 and 2012 (moderate increase in 2012). In the chemical fertilizer treatments, there was a reduction in seed yield, straw yield and nutrient uptake of canola when only N fertilizer was applied compared to the control (significant in 2010 and 2011). Application of P along with N (NP) increased seed yield, straw yield and nutrient uptake of canola compared to N alone treatment, but was less than the NPS treatment in all years. Application of S along with N (NS) increased seed yield, straw yield and nutrient uptake of canola further compared to the NP treatment, but it was still lower than the NPS treatment in 2010 and 2011. In treatments receiving inorganic/mineral amendments in addition to chemical fertilizers, application of N + P fertilizers substantially increased seed yield, straw yield and nutrient uptake in treatments receiving gypsum and RRES in 2009, 2010, 2011 and 2012. This suggests the potential of gypsum and RRES in preventing S deficiency in organic crops when grown on S-deficient soils, provided other nutrients are not limiting in the soil for crop growth. Seed yield, straw yield and nutrient uptake with application of N and S fertilizers in combination with rock phosphate and/or Penicillium bilaiae were similar to N + S treatment in most cases, except in 2011 when application of finely-ground or powder rock phosphate in a combination with N + S produced significantly greater yield and nutrient uptake than N + S with granular rock phosphate. This suggests little contribution of rock phosphate and/or Penicillium bilaiae in improving yield and nutrient uptake of canola, and improves the performance of fine rock phosphate only evident in the third growing season in 2011, after three consecutive applications, but not in 2012. In conclusion, some organic amendments showed potential for improvement in organic crop production, and in some other cases highest yield and nutrient uptake were

Effects of broad-leaf crop frequency in various rotations on soil organic C and N, and inorganic N in a Dark Brown soil

The objective of this study was to determine the impact of frequency of broad-leaf crops canola and pea in various crop rotations on pH, total organic C (TOC), total organic N (TON), light fraction organic C (LFOC) and light fraction organic N (LFON) in the 0 - 7.5 and 7.5 - 15 cm soil depths in autumn 2009 after 12 years (1998-2009) on a Dark Brown Chernozem (Typic Boroll) loam at Scott, Saskatchewan, Canada. The field ex-periment contained monoculture canola (herbicide tolerant and blackleg resistant hybrid) and monoculture pea compared with rotations that contained these crops every 2-, 3-, and 4-yr with wheat. There was no effect of crop rotation duration and crop phase on soil pH. Mass of TOC and TON in the 0 - 15 cm soil was greater in canola phase than pea phase in the 1-yr (monoculture) and 2-yr crop rotations, while the opposite was true in the 3-yr and 4-yr crop rotations. Mass of TOC and TON (averaged across crop phases,) in soil generally increased with increasing crop rotation duration, with the maximum in the 4-yr rotation while no difference in the 1-yr and 2-yr rotations. Mass of LFOC and LFON in soil was greater in canola phase than pea phase in the 1-yr, 2-yr and 3-yr rotations, but the opposite was true in the 4-yr rotation. There was no consistent effect of crop rotation duration on mass of LFOC and LFON. The N balance sheet over the 1998 to 2009 period indicated large amounts of unaccounted N for monoculture pea, suggesting a great potential for N loss from the soil-plant system in this treatment through nitrate leaching and/or denitrification. In conclusion, the findings suggest that the quantity of organic C and N can be maximized by increasing duration of crop rotation and by including hybrid canola in the rotation.