Nitrogen dynamics of grass as affected by N input regimes, soil texture and climate: lysimeter measurements and simulations

摘要: Nitrate leaching is often low from grasslands, primarily due to their long period of N uptake compared arable crops. In the present paper we explore combined effects input regime, soil type and climatic conditions through a combination field lysimeter studies simulation modeling temporary grassland. A consisting eight 10 × 4 1 m individually drained cells was constructed in SW Norway, region with cool wet marine climate. Six were filled silty sand two coarse sand. The lysimeters cropped first barley for years, followed by five years Treatments included various combinations (fertilizer, manure or both), results analyzed means coupled dynamic models (CoupModel: heat- water transport model, SOILN–NO: nitrogen model). parameterized further used assess scenario more continental climate (somewhat cooler drier). All treatments resulted net export N, amounts removed at harvest ranging between 121 139% that applied. Measured yield treatment receiving only almost as high fertilizer only, even though it received on average about 80 kg ha−1 less inorganic N. Nitrogen losses range 5–23% input, had greater effect than source input. fraction leachate 71–82% total 98% this nitrate. gave reasonable yields well timing magnitude nitrate different treatments. They also clearly illustrated system attributable plant uptake. using weather data drier showed large decline outside main cropping season, but simulated nevertheless significantly lower. With scenario, precipitation 50% actual experimental site, lower temperatures during autumn winter reduced mineralization organic significantly. Thus, reduction apparently outweighed shorter growing season scenario.