@article{icrisat3559,
            year = {1994},
           title = {Increased proportion of active soil N in Breton loam under cropping systems with forages and green manures},
            note = {The Farming for the Future Program of the Alberta Agriculture Research Institute, as well as Natural Sciences and Engineering Research Council of Canada, provided financial support. We thank J. Konwicki, C. Nguyen, J. Brown and J. Thurston for technical assistance and S. Nakashima for word processing asslstance.},
          volume = {74},
          number = {1},
           pages = {67--74},
          author = {S P Wani and W B McGill and K L Haugen-Kozyra and N G Juma},
       publisher = {Agricultural Institute of Canada},
         journal = {Canadian Journal of Soil Science},
             url = {http://oar.icrisat.org/3559/},
        abstract = {Total soil N and N mineralization
rate partially ctririct\&iie the influence olvariouJcropping systems on the growth of.sequent.crop.s in a rotation' The objectives
of this study were to (1) quantify the relationship among cropping system, total N and mineralizable N, and (2) compare amount
of N mineralized under'controlled laboratory conditions-with pianl N uptake under green]ouse conditi:ns. Three cropping systems
that have been in operation between 9 and 60 yr on a Gray-Luvisol (Breton loam; were
{\^{ }}selected . They included: (1) an ag.lo:
ecological (lnn) d-yr rotation involving fabibeans as gr-een manure (AER1 sampled after the\_first lababean crop-?nq AER?
,u-pied after 3 yr of continuous forage)l (2) continuous grain system (CG), with fertilizer N at 90 kg ha-'{\^{ }}yr- '; inttrated
in 1980 and considered established in f"98i; i3) a classicial Ereton iotation (CBR) involving 9]o-ng-term (ca. 1930) 5-yr rotation
with forages and cereals and no return of.ciop residues (CBR1 fertilized with P-K-S and CBR2 unfertilized). We cautio\_n that
not all ohlses of each rotation were sampled: bur conclusions pertain to N-mineralization potential in soil samples immediately
preceding barley as sequent crop in each rotation. The rate ofN mineralization declined with time, but it remained greater than
iero aftei 20 wi{\ensuremath{<}} of incirbation in all soils. Mineral-N accumulation at 20 wk followed the order AER1 {\ensuremath{>}} AER2 {\ensuremath{>}} {\ensuremath{>}} CBRI {\ensuremath{>}}
CBR2 : CG. Mineralizable soil N, following one cycle of the AER rotation, was almost double that following 60 yr of the
CBR rotation. Data for mineral-N accumulation under laboratory conditions were described best by a single-component expo-n-ential
model. Legume-based rotations were associated with increased total soil N and a greater proportional increase in active N than
in total soilN. Active N was least in soil under the CG system. The incubation-extraction procedure resulted in higher estimates
of mineralizable N than did the plant-uptake method; liowever, the ranking of N-supplying power of soils was the same.},
        keywords = {Cropping systems, Gray Luvisol, N mineralization, soil quatity, Typic Cryoboralf}
}