Net N-mineralisation related to soil organic matter pools

Abstract

Soil organic ma�er and its turnover rate are key parameters for agricultural management practice as well as for environmental issues. In a field experiment comparing organic (compost) and mineral fertilisation and combinations of both the amount of inorganic nitrogen in the soil and the nitrogen uptake by the plants were measured. Considering these data and the fertilisation practice the net N-mineralisation during the vegetation periods 1996-2001 was estimated for six fertilisation treatments. Simultaneously the nitrogen dynamics in the soil were calculated using the STOTRASIM model, which takes into account four soil organic ma�er pools of different turnover rate. A close relation was found between the amount of a slow decomposable fraction and the net N-mineralisation during the vegetation period. composting plant of the City of Vienna was used. The compost raw material consisted of sourceseparated organic waste, which included organic household waste and yard trimmings at a 2:3 ratio. The compost was produced in an open windrow process with regular turning using front-end loader and windrow turner.The amount of inorganic nitrogen in the soil (NO 3 -N + NH 4 -N for the depth of 0-90 cm) was measured periodically in each plot and the yield and the nitrogen uptake by the plants were determined annually. For the six plots investigated in detail the net-N-mineralisation during the vegetation periods 1996-2001 is calculated using the following equation assuming that inorganic N-input from the atmosphere is compensated by gaseous losses (Table 1) ModellingThe water fluxes in the soil and plant growth are calculated with the deterministic simulation model SIMWASER (Stenitzer 1988) and the nitrogen dynamics in the soil and accordingly the losses of nitrate to the groundwater are calculated with STOTRASIM (Feichtinger 1998). The models describe one-dimensional, vertical flow of water and nitrate-nitrogen within a soil profile, neglecting interflow and preferential flow.SIMWASER simulates the water balance for a soil profile and the crop yield of any number of crop rotations and years on a daily basis, provided that daily weather records are available. The water balance and the growth of plants are interrelated by the physiological interaction of assimilation and transpiration. Potential assimilation and therefore potential plant growth occurs as long as the water supply towards the stomata can meet the potential transpiration loss. The potential growth rate is specific to each crop and depends mainly on air temperature and global radiation. The potential plant production rate and the proportion of actual transpiration to the potential one calculate actual plant growth. The potential evapotranspiration is calculated according to the Penman-Monteith-for- Szeicz et al. 1969, Thom et Oliver 1977 and the potential transpiration is deduced from the potential evapotranspiration. The actual transpiration is the amount of water, which can be withdrawn by the roots from the soil and is less equal to the potential tra...

Assessing soil amendment potentials of Mucuna pruriens and Crotalaria juncea when used as fallow crops

“…The results indicate a significant (p < 0.05) difference in the levels of potassium between M. pruriens and C. juncea but showed no significant difference in the natural regeneration before planting and after incorporation of the plant materials in the soil. This confirms the findings of Feichtinger et al (2004) that, the use of M. pruriens and C. juncea can conserve the moisture, builds up organic matter and improves the properties of terrestrial soil and activity of microbes supporting the mineralization rate and release of potassium in greater proportion in the soil. Although the incorporation of Mucuna and Crotalaria led to increase in potassium levels, C. juncea (89.71 Mg/kg) added a higher amount of available potassium as compared to M. pruriens (69.51 Mg/kg).…”

Changes in soil organic matter over 18 years in Prince Edward Island, Canada

“…Soil organic matter is a good index of soil quality and is known to be impacted by the crops grown, the use of soil organic amendments (Carter et al 2004;Carter 2007;Grandy et al 2002;Nyiraneza et al 2009Nyiraneza et al , 2010, crop residue management practices (Karlen et al 1994;Kapkiyai et al 1999), the soil type (Prasad and Power 1997;Hu et al 2014), and climate conditions. Soil organic matter is a reservoir of macro-and micronutrients, and their availability is affected by microbial activity (Feichtinger et al 2004). The benefits of increased SOM levels are associated with enhanced nutrient availability and soil physical properties, including increased water-holding capacity.…”

Effects of agricultural management on soil organic matter and carbon transformation - a review

“…SOM is a major terrestrial pool for C, N, P, and S, and the cycling and availability of these elements are constantly being changed by microbial immobilization and mineralization (Hillel 1991, Feichtinger et al 2004. The importance of increased SOM or soil organic carbon (SOC) is its effect on improving soil physical properties, conserving water, and increasing available nutrients.…”