Eight years of crop rotation and tillage effects on crop production and N fertilizer use

et al. 2006

Self Cite

. 2006. Nitrogen release during decomposition of crop residues under conventional and zero tillage. Can. J. Soil Sci. 86: 11-19. The litter-bag method was used in field experiments to determine nitrogen (N) loss patterns from decomposing red clover (Trifolium pratense) green manure (GM), field pea (Pisum sativum), canola (Brassica rapa) and monoculture wheat (Triticum aestivum) residues under conventional and zero tillage. Nitrogen contained in crop residues ranged from 10 kg ha -1 in wheat under both tillage systems to 115 kg ha -1 in clover GM under zero tillage. The patterns of N loss (i.e., release), particularly from GM residues, over 52-wk periods varied with tillage, i.e., residues lost N more rapidly under conventional tillage than under zero tillage in the first 5 to 10 wk after residue placement. Net N immobilization was sometimes observed, particularly under zero tillage. Where net N release occurred, it ranged from 22% of wheat N under conventional tillage to 71% for clover N under conventional tillage; it was positively correlated with residue N concentration and microbial activity, and negatively correlated with C:N and lignin:N ratios in one study period. The amounts of N released were 2 kg ha -1 from wheat, 10 to 25 kg ha -1 from canola, 4 to 18 kg ha -1 from pea, and 46 to 69 kg ha -1 from GM residues. Therefore, when grain is harvested, the remaining crop residues do not release much N to the soil in the first year of decomposition, but the N stored in soil is presumably released in subsequent years.

Section: Methodsmentioning

confidence: 99%

Section: Initial Crop Residue Quality and N Addedmentioning

confidence: 97%

Nitrogen release during decomposition of crop residues under conventional and zero tillage

Lupwayi¹,

Clayton²,

et al. 2006

Self Cite

“…Each phase of the rotation was present each year. Agronomic details of the trial have been described by Soon and Clayton (2002). Conventional tillage consisted of fall cultivation to 10-15 cm depth with a heavy-duty cultivator or disc, and two spring tillage operations with a field cultivator, followed by harrowing and packing.…”

Section: Methodsmentioning

confidence: 99%

Potassium release during decomposition of crop residues under conventional and zero tillage

Lupwayi¹,

Clayton²,

et al. 2006

. 2006. Potassium release during decomposition of crop residues under conventional and zero tillage. Can. J. Soil Sci. 86: 473-481. Nutrient cycling is an important part of integrated nutrient management. The litterbag method was used in field experiments to determine potassium (K) release patterns from red clover (Trifolium pratense) green manure (GM), field pea (Pisum sativum), canola (Brassica rapa) and monoculture wheat (Triticum aestivum) residues under conventional and zero tillage from 1998 to 1999 and from 1999 to 2000. Potassium contained in crop residues ranged from 25 kg ha -1 in wheat to 121 kg ha -1 in pea residues, both under zero tillage. The percentage of K released over a 52-wk period ranged from 65% of pea K under zero tillage to 99% of clover K under conventional tillage, and the amounts released were 20-32 kg ha -1 from wheat, 31-52 kg ha -1 from canola, 28-79 kg ha -1 from pea, and 31-118 kg ha -1 from legume GM residues. In both trial periods, K from wheat residues was released at a faster rate under conventional tillage than under zero tillage during the first 10 wk of residue decomposition. In contrast, K from pea and canola residues was released more quickly under zero tillage than under conventional tillage. The effect of tillage on K release from GM residues was similar to that on pea and canola residues in 1998-1999, but similar to that on wheat residues in 1999-2000. Correlations between K release and residue quality were inconsistent, presumably because K is not a structural component of plant tissue, and therefore its release is probably related more to leaching than to residue decomposition. These results show that crop residues recycle substantial amounts of K for use by subsequent crops in rotation. Lors des deux périodes d'expérimentation, les résidus de blé ont libéré plus rapidement le potassium quand le sol était travaillé que quand il ne l'était pas durant les 10 premières semaines de décomposition. Les résidus de pois et de canola, en revanche, libèrent le K plus vite quand le sol n'est pas travaillé. Le travail du sol a permis aux résidus de EV de libérer le K de la même façon que les résidus de pois et de canola en 1998-1999, mais en 1999-2000, l'effet se rapprochait davantage de celui observé avec les résidus de blé. La corrélation entre la libération du K et la qualité des résidus n'est pas cohérente, sans doute parce que le K n'entre pas dans la structure des tissus végétaux. Sa libération est donc probablement plus reliée à la lixiviation qu'à la décomposition des débris végétaux. Ces résultats révèlent que les résidus agricoles recyclent une quantité appréciable de K que les cultures subséquentes peuvent utiliser.

“…The main plots were tillage treatments (conventional tillage and zero tillage) and the subplots consisted of different crop sequences in rotation (Lupwayi et al 2004). The agronomic details of the trial have been described by Soon and Clayton (2002). Conventional tillage consisted of fall cultivation to 10-to 15-cm depth with a heavy-duty cultivator or disc, and two spring tillage operations with a field cultivator.…”

Section: Field Experimentsmentioning

confidence: 99%

Soil microbiological properties during decomposition of crop residues under conventional and zero tillage

Lupwayi¹,

Clayton²,

et al. 2004

Self Cite

Soil microbiological properties during decomposition of crop residues under conventional and zero tillage. Can. J. Soil Sci. 84: 411-419. Field experiments were conducted to correlate decomposition of red clover (Trifolium pratense) green manure (GM), field pea (Pisum sativum), canola (Brassica rapa) and wheat (Triticum aestivum) residues, and soil organic C (SOC), under zero tillage and conventional tillage, with soil microbial biomass C (MBC), bacterial functional diversity and microbial activity (CO 2 evolution). A greenhouse experiment was also conducted to relate crop residue quality to soil microbial characteristics. Zero tillage increased MBC only in the 0-to 5-cm soil layer. Soil MBC decreased more with soil depth than either microbial diversity or total SOC. Legume GM residues induced greater initial CO 2 evolution than the other residues. This means that results that do not include the initial flush of microbial activity, e.g., by sampling only in the season(s) following residue placement, probably underestimate gas evolution from legume crop residues. Residue N, P and K contents were positively correlated with microbial functional diversity and activity, which were positively correlated with crop residue decomposition. Therefore, microbial functional diversity and activity were good indicators of microbial decomposition processes. Residue C/N and C/P ratios (i.e., high C content) were positively correlated with MBC, which was positively correlated with SOC. Therefore, soil MBC was a good indicator of soil quality (soil organic matter content). Les auteurs ont effectué des essais sur le terrain en vue de corréler la décomposition de l'engrais vert (EV) de trèfle des prés (Trifolium pratense) et des résidus de pois de grande culture (Pisum sativum), de canola (Brassica rapa) et de blé (Triticum aestivum) ainsi que la concentration de C organique dans le sol (COS) avec la biomasse microbienne du sol (BMS), la diversité fonctionnelle de la microflore et l'activité microbienne (évolution du CO 2 ) quand le sol est travaillé de la manière usuelle ou n'est pas travaillé. Ils ont aussi réalisé une expérience en serre pour établir le lien entre la qualité des déchets de culture et les propriétés de la microflore tellurique. Le non-travail du sol n'augmente la BMS que dans la couche supérieure de 0 à 5 cm du sol. La BMS diminue plus avec la profondeur qu'avec la diversité de la microflore ou la concentration totale de COS. Les résidus d'EV de légumineuses entraînent une évolution initiale plus rapide du CO 2 que les résidus d'une autre nature. On en déduit que les résultats ne tenant pas compte de l'explosion d'activité initiale de la microflore (à savoir obtenus uniquement après échantillonnage du sol la ou les saisons suivant l'incorporation des résidus) pourraient sous-estimer l'évolution gazeuse des résidus de légumineuses. La concentration de N, de P et de K dans les résidus présente une corrélation positive avec la diversité fonctionnelle et le degré d'activité de la microflore, qui sont elles-mêmes corré...