No abstract

No abstract

The ability of light-textured soils to retain nutrients and water is small. In agriculture such soils pose a risk of nutrient leaching when amended with fertilizers. This study investigated the effects of the incorporation of activated carbon (AC) into the soil to determine (i) if it would decrease leaching of major nutrient ions and (ii) if its effect on leaching is influenced by fertilizer use. Nitrate nitrogen (NO 3 − -N), ammonium nitrogen (NH 4 + -N), phosphorus (P) and potassium (K) leaching through two substrates (sandy loam soil (S) and a sandy loam soil mixed with activated carbon (S + AC), which were unfertilized (NF or control) or fertilized with inorganic fertilizer (F), pig slurry (PS), pig slurry digestate (PD) or sewage sludge digestate (SD) was studied using mini-lysimeters. In soil enriched with AC mark K-835, water percolation and NO 3 − -N and P leaching were significantly reduced, and K leaching was increased. Ammonium nitrogen leaching was not influenced by the AC amendment. The impact of AC on NO 3 − -N and P leaching and water percolation did not change during the two-year period, from which it is concluded that AC mark K-835 prevents the leaching of NO 3 − -N and P and increases soil water retention ability, and thus it is beneficial for light-textured soils.

In grassland areas where herbage production has no economic value, the cut grass is often left on the sward surface where its decomposition is influenced by weather conditions. Although the influence of temperature and humidity on decomposition has been investigated under controlled lab conditions, experimentation has generally been under ideal moisture conditions that have not tested the combinations of climatic limitations that might occur in the field. The decomposition of mown turfgrass clippings deposited at different times of vegetation period was studied in situ using nylon bags during the first 8 weeks after deposition to investigate the effect of weather conditions (the air temperature, relative humidity, precipitation) on decomposition. Decomposition is the highest in the case of high air humidity and temperature of 108C. Limiting factors for decomposition at temperatures above 108C is the air humidity and below 108C the air temperature. The general tendency was that the rate of decomposition increased with increasing air temperature up to 108C, but with further increases of air temperature the decomposition rate slowed down. Relative air humidity had a variable impact (at the beginning of the decomposition process (weeks 1Á2) the influence was negative, during weeks 3Á8 of the decomposition process the effect was positive), and hence had no generalized relationship with decomposition over the studied decomposition period (weeks 1Á8). The most significant influence of weather conditions on the decomposition rate was recorded directly after cutting. If the cutting was done during hot weather conditions, the material was drying fast and therefore decomposed slowly. Our results indicate that for fast decomposition of clippings it is important to maintain the freshness of material. Lower decomposition rates occurred during conditions of hot and dry weather, and also cooler (temperature near to 08C) weather, and can be compensated as soon as favourable weather arrives.

No abstract