The Effects of Mixing Rates and Incorporation Timing Differences of Green Manure Plants on Some Ecosystem Functions of Soil under Mediterranean Climate Biodegradability Conditions
Project no. 20546 · Status: Kapanmış (Yayın bekleniyor) · 2019
Summary
The present study was designed to determine the effect of incorporation times and mixing rates, which are suitable for the green manuring purposes, of vetch (Vicia sativa var. Alper) and barley (Hordeum vulgare var Sancak) plants, which have adapted to this region and can easily be adopted by the farmers, on mineralization processes and microbial activity in the agricultural soils under Mediterranean climatic conditions. Based on this point, the experiment was conducted in randomized block design with three replications in a Typic Xerorthent soil in Ahmetli district of Manisa province to test the green manuring performances of the Vetch plant (F) as legume and the Barley plant (A) as a non-legume. For this purpose, three different rates of mixed green manure plants as 100%F+0%A, 80%F+20%A and 60%F+40%A were incorporated in the soil at two different times, 10% and 90% flowering periods. Basal soil respiration (BSR), nitrogen mineralization (Nmin), dehydrogenase (DHG), alkaline phosphatase (ALKPA) and ß-glucosidase (GLU) enzyme activities and mineral nitrogen forms asNH4-N and NO3-N analyzes were performed in the soil samples taken from a depth of 0-20 cm in seven sampling periods in total as follows: once every week in the first month, once every two weeks in the second month, and once in the third month after incorporating into the soil. In addition, green biomass yields were determined before incorporating green manure plants. The effect of soil sampling time (PERIOD; 1-7), different green fertilization patterns (TREATMENT; 1-8) and interactions (PERIODxTREATMENT), which are independent variables in our study, on soil microbial properties analyzed were found to be significant (P <0.01). All treatments obtained significant changes on microbial parameters compared to control plots (P <0.05). According to the analysis results, while an average of 35% increase (between 14% and 77%) was obtained in the microbial activity and mineral nitrogen concentrations for 10% flowering plots, the increase was in the range of 9% - 117% in 90% flowering plots with an average of 55%. It is thought that more microbial activity has been achieved as a result of the increase in the amount of fresh biomass entering the soil (33%) during the flowering period of 90%. Both the presence of barley plant in the mixture and its increase in its rate in the mixture caused BSR, Nmin, DHG, ALKPA, UA and GLU values to increase and make this more sustainable over the period. According to the results of PCA analysis, the variables that showed their weight in the first factor by explaining the variance most were the DHG, GLU, Nmin and BSR variables called “C- and N-mineralization”. Among the prominent results of the correlation analysis were (a) positive relationship between NH4-N and soil moisture since the increase in ammonification in the soil can also occur with the increase of soil moisture (r = 0.180); (b) negative correlation (r = -0.255) between DHG and NO3-N resulting from decreased DHG activity with increased concentration of nitrates that function as an alternative electron acceptor (r = -0.255) and (c) negative correlation (r = -0.191) between UA and NH4-N, that reveals the suppression of enzyme activity in connection with the increase in the amount of NH4-N which is the final product of UA activity. Considering the results of the study, it is recommended to mix the mixture green manure plants consisting of 60% vetch and 40% barley plants as green fertilizer into the soil during 90% flowering period in order to find solutions to soil exhausting and improve soil health in areas under the arid and semi-arid Mediterranean climate. For the purpose of sowing or transplanting the main crop after green fertilization, it can be suggested to give 30 days interval for biological and microbiological stabilization of the soil.