Processes And Mechanism On Some Behaviors Of Nitrogen In Turf Under Different Managements

Pool and pot-culture experiments were carried out to study the sources, moving directions and losses of nitrogen in grassland. This paper studied the nitrogen in air absorbed by the turfgrass seedlings under N deficiency conditions, measured the changes of nutrient content and the ammonia volatilization of grassland under different controlled release fertilizers application and management on turf, researched the nitrogen loss leaching from turfgrass after fertilization, which provided scientific basis for figuring out the nitrogen behavior in grassland and making the theory of nitrogen cycle in grassland ecosystems perfect. The results showed that as follows:1. The turfgrass seedlings absorbed the nitrogen in air under N deficiency conditions during seed germination and the period of seedling growth, the absorption more concentrated in the later germination period and the N uptake was increased with plant growth.2.The ammonia volatilization flux had positive correlation with the fertilizer application rate, while the ammonia volatilization loss rate had negative correlation with the fertilizer application rate. With the amount of applied fertilizer increased, the concentrations of NH4+-N in surface soil and the NO3--N in soil increased, the N level of turfgrass raised.3. The ammonia volatilization flux and loss rate were decrease with increase of fertilization depth, but the ammonia volatilization flux and loss rate were the lowest when the fertilization depth was6cm. The concentrations of NH4+-N in surface soil was decrease with increase of fertilization depth while the concentrations of NO3-N in soil and the NH4+-N in deep soil and the N content of turfgrass were overall increased. The concentrations of NH4+-N in deep soil and the N content of turfgrass were the highest when the fertilization depth was6cm.4. The ammonia volatilization flux and loss rate were decreased with raised of irrigation minima. With the irrigation minima raised, the concentrations of NH4+-N and NO3--N in surface soil decreased, the concentrations of NH4+-N and NO3--N in deep soil and the N level of turfgrass had no regularity change, the concentrations of NH4+-N and NO3--N in deep soil were the highest in70%FC and were the lowest in60%FC, the N level of turfgrass in the later fertilization period is as follows:60%FC>70%FC>50%FC>80%FC.5.With the stubble height was lower, the ammonia volatilization flux and loss rate were decreased, and the concentrations of NH4+-N and NO3-N in surface soil decreased, while the concentrations of NO3--N in deep soil decreased but non-significant.the concentrations of NH4+-N in deep soil was the highest when the stubble height was6cm. The N level of turfgrass reduced with the stubble height increased.6. Sprinkling irrigation can cause nitrogen leaching from turfgrass. The nitrogen leaching loss from turfgrass was3.90g/kg in30min when the sprinkler irrigation strength was12mm/h.There was significantly positive correlation between the nitrogen loss leaching from turfgrass and the sprinkler irrigation time, sprinkler irrigation strength and the amount of applied fertilizer.sprinkler irrigation after lawn mowing also can increase the nitrogen leaching loss.