TY - JOUR

T1 - Estimating net N mineralization under unfertilized winter wheat using simulations with NET N and a balance approach

AU - Heumann, Sabine

AU - Ratjen, Arne

AU - Kage, Henning

AU - Böttcher, Jürgen

N1 - Funding information: We wish to thank Silke Bokeloh and Ulrike Pieper for their excellent work in the laboratory as well as Marianne Fritzensmeier, Dorit Ebner, Franziska Meyer-Schatz, Horst Ringe, Hubert Groh and Andreas Krimphoff for dedicated numerous field measurements. The study was funded by the “Deutsche Bundesstiftung Umwelt” (German Federal Environmental Foundation), Osnabrück.

PY - 2014/1/1

Y1 - 2014/1/1

N2 - Eliminating uncertainty in soil N supply could reduce fertilizer input, but the amount of N mineralized during plant growth is usually still unknown. We aimed to test the relatively simple twopool net N mineralization model NET N that uses sitespecific temperature and soil water functions as well as pedotransfer functions for deriving the pool sizes and was developed for NW Germany. The objectives were to (1) evaluate, if field net N mineralization under unfertilized winter wheat could be satisfactorily simulated, and to (2) examine the variation in time patterns of net N mineralization within years and sites and from two functional N pools: a rather small, fast mineralizable N pool (Nfast) and a much greater, slowly mineralizable N pool (Nslow). NET N simulations for 36 site-year-combinations and up to five dates within the growing season were evaluated with detailed N balance approaches (calculated from: soil mineral N contents, plant N uptake using estimates of green area index, simulated N leaching). Simulated net N mineralization was highly significantly correlated (r2 = 0.58; root mean square error = 24.2 kg N ha-1)to estimations from the most detailed balance approach, with total simulated net N mineralization until mid August ranging from 62.1 to 196.5 kg N ha-1 . It also became evident that N mineralization from pool Nslow—in contrast to pool Nfast—was considerably higher for loess soils than for sandy or loamy soils. The results suggest that NET N was adequate for simulations in unfertilized winter wheat. However, further field studies are necessary for proving its applicability under fertilized conditions.

AB - Eliminating uncertainty in soil N supply could reduce fertilizer input, but the amount of N mineralized during plant growth is usually still unknown. We aimed to test the relatively simple twopool net N mineralization model NET N that uses sitespecific temperature and soil water functions as well as pedotransfer functions for deriving the pool sizes and was developed for NW Germany. The objectives were to (1) evaluate, if field net N mineralization under unfertilized winter wheat could be satisfactorily simulated, and to (2) examine the variation in time patterns of net N mineralization within years and sites and from two functional N pools: a rather small, fast mineralizable N pool (Nfast) and a much greater, slowly mineralizable N pool (Nslow). NET N simulations for 36 site-year-combinations and up to five dates within the growing season were evaluated with detailed N balance approaches (calculated from: soil mineral N contents, plant N uptake using estimates of green area index, simulated N leaching). Simulated net N mineralization was highly significantly correlated (r2 = 0.58; root mean square error = 24.2 kg N ha-1)to estimations from the most detailed balance approach, with total simulated net N mineralization until mid August ranging from 62.1 to 196.5 kg N ha-1 . It also became evident that N mineralization from pool Nslow—in contrast to pool Nfast—was considerably higher for loess soils than for sandy or loamy soils. The results suggest that NET N was adequate for simulations in unfertilized winter wheat. However, further field studies are necessary for proving its applicability under fertilized conditions.

KW - Green area index (GAI)

KW - Non-destructive canopy measurements

KW - Plant N uptake

KW - Soil N supply

KW - Soil water content

UR - http://www.scopus.com/inward/record.url?scp=85027944977&partnerID=8YFLogxK

U2 - 10.1007/s10705-014-9616-y

DO - 10.1007/s10705-014-9616-y

M3 - Article

AN - SCOPUS:85027944977

VL - 99

SP - 31

EP - 44

JO - Nutrient cycling in agroecosystems

JF - Nutrient cycling in agroecosystems

SN - 1385-1314

IS - 1

ER -