Tomas Persson
Research Scientist
(+47) 466 30 485
tomas.persson@nibio.no
Place
Særheim
Visiting address
Postvegen 213, NO-4353 Klepp stasjon
Authors
Mohammad Tirgariseraji A. Pouyan Nejadhashemi Mahmood Sabouhi Sabouni Yaghoob Jafari Tomas Persson Alisher Mirzabaev Alireza Nikouei Kieron Moller Naser Shahnoushi ForoushaniAbstract
Food production is the primary source of nitrogen pollution, which has significantly impacted the nitrogen cycle and exceeded the nitrogen-safe operation space of the planet. The objective of this study is to assess the effectiveness of the Nitrogen Regulatory Policy (NRP) in reducing nitrogen fertilizer use under population pressure for meat, dairy, wheat, and potatoes in the Zayandeh-Rud River basin, Iran. The methodology of this study involves two main components. First, an elasticity criterion was formulated to assess the trade-off between nitrogen fertilizer use and food production capacity. This criterion integrates optimized cropland, the Block of Distributed Calories (BDC), and nitrogen fertilizer use, with food production capacity quantified in terms of the BDC at its optimal level. Second, the simulated distribution of the elasticity criterion was analyzed using Simulation and Econometrics to Analyze Risk (Simetar), defining elastic and inelastic zones to capture the variability in the trade-off under different conditions. The results of this study identified key factors influencing the elastic and inelastic ranges of the elasticity criterion, including technological change, the weight of diet components in dietary preferences, and the diminishing returns of the NRP. The NRP solution aims to reduce nitrogen fertilizer use by targeting a lower application range. It addresses the challenges of fertilizer management under population pressure, specifically for farming systems in the Zayandeh-Rud River basin operating at the ‘diminishing marginal production’ stage. The trade-off between livestock and non-livestock diet components enhances nitrogen fertilizer efficiency under population pressure as long as livestock components remain within the elastic zone and non-livestock components stay within the inelastic zone. The novelty of this study lies in the introduction of the elasticity criterion for nitrogen fertilizer use under population pressure. This innovative metric highlights the risk of ineffective trade-offs between food production capacity and nitrogen fertilizer adjustments, offering a crucial tool to guide sustainable agricultural practices within the defined criterion ranges.
Authors
Jian Liu Hilmar Tor Sævarsson Marianne Bechmann Tore Krogstad Tomas Persson Anne Falk ØgaardAbstract
Purpose Losses of phosphorus (P) and carbon (C) from livestock farming impair downstream water quality, requiring a better understanding of their leaching processes. The aim of the study was to examine how leaching of P (total dissolved P – TDP; dissolved reactive P – DRP; dissolved organic P – DOP) and dissolved organic C (DOC) was affected by soil type, chemical property and amendment. Methods Leaching experiments with simulated rain were conducted on five different mineral and organic soils before and after a manure or mineral fertilizer application, respectively. The soils were: Fluvisol, Stagnosol, Umbrisol, Histosol (Ruptic), and Histosol. Profile-long soil columns were used, and chemistry of soil and water samples were studied. Results Before the P addition, the Histosol (Ruptic) soil with high P and organic matter contents but low sorption in the subsoil had significantly greatest flow-weighted mean concentrations (FWMCs) of TDP (315 versus 33‒48 µg L‒1), DRP (215 versus 5‒26 µg L‒1), DOP (101 versus 19‒33 µg L‒1) and DOC (46 versus 8‒25 mg L‒1) in drainage water among all soils. Leaching of DOC varied more than TDP, DRP and DOP across most soils. The manure application significantly elevated FWMCs-TDP in three soils than before the application and led to greater FWMCs-TDP in all soils and FWMCs-DOC in most soils than mineral fertilizer did. The ratios of DRP to DOP and to TDP were significantly correlated to whole-profile degree of P saturation (DPS) of the soils (R2 > 0.9, p < 0.05). Conclusion Sorption/desorption characteristics of subsoils greatly affected concentrations and loads of P and DOC in drainage, as well as the ratios of DRP to DOP and to TDP. Therefore, sorption/desorption characteristics and DPS of subsoils should be included in the work of assessing dissolved P and DOC leaching and developing nutrient mitigation measures.
Abstract
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