The effect of land management and organic matter inputs on bacterial population and soil nutrients across different types of agroforestry system

Abstract

Abstract. Rinady MVP, Nuraini Y, Prayogo C, Arfarita N. 2023. The effect of land management and organic matter inputs on bacterial population and soil nutrients across different types of agroforestry system. Biodiversitas 24: 1333-1345. Different management of agroforestry systems changes crop composition and growth. This will affect organic matter inputs that become the source of food and energy for soil microorganisms. The soil organisms themself play an important role in amplifying soil biogeochemical processes and regulating soil reactions. This process allows the nutrients to be released into the soil and absorbed by the crop. This study aimed to examine the abundance of soil bacterial population and the changes in soil chemical properties (soil pH, total soil organic carbon (C), and total soil N (Nitrogen) under different land management and organic matter inputs. The determination of total organic C and total soil N was used by Walkey and Black and Kjedahl methods. Total Plate Count (TPC) techniques were employed to measure Total Bacteria Population (TBP) and Total Cellulolytic Bacteria (TCB). The Randomized Complete Block Design was used along with the 5% Tukey's test to examine the significant effect of the treatments. These treatments consisted of various agroforestry system as follow: (i) pine-coffee agroforestry system (PK), (ii) pine-banana agroforestry system (PPs), (iii) pine-cardamom agroforestry system (PR), (iv) pine-vegetable agroforestry system (PS), (v) mixed garden (KC), and (vi) citrus (LJ). Each treatment was repeated four times to obtain 24 experimental plots using a size of 20 m x 20 m. The results showed that the highest organic C and N content was obtained at the PK (agroforestry of pine at 41 years and coffee at 11 years old) plot, which was about 6.64% and 0.56%. Those parameters strongly correspond to the greatest soil bacteria population and soil cellulolytic bacteria population at the value of 1,71 x 105 CFU/g and 4,24 x 104 CFU/g, resulting from the greatest quantity of in-situ litter accumulation at PK plot to reach about 201.35 g. The dry weight value of litter in situ at the PK plot is greater than that of the PS and LJ plots by 81% and 87%. A power equation followed the relationship between soil organic C and the total bacteria population. A similar trend has been observed between total soil Nitrogen and total bacteria population. We concluded that changes in different management could affect soil chemical conditions and the changes in the total population of soil bacteria and cellulolytic soil bacteria.

The impact of different management on pine-based agroforestry system and litter accumulation on the population and activity of cellulolytic bacteria

“…The PV plot had the lowest litter thickness, which was not significantly different from the CO plot. The greater the percentage of canopy cover, the more litter production is produced (Rinady et al 2023;Azizah et al 2023). Leaves reduce the intensity of sunlight exposure, slowing wind speed and rainfall rate.…”

“…Fallen litter contains soil nutrients that plants cannot directly use (Prayogo et al 2021a;Prayogo and Arfarita 2022). Therefore, the litter must first be decomposed by soil microbes (bacteria), which greatly affect the availability of nutrients, and these nutrients can create fertile soil conditions (Sudomo and Widiyanto 2017;Rinady et al 2023). The litter layer protects plants from direct rainwater, sunlight penetration, and temperature changes while facilitating water and air circulation.…”

“…The C/N ratio is a crucial indicator for high-quality organic crop residue, enhancing soil fertility since the nutrient can release quickly, for example Cabbage litter which was found mainly at PV plot. Banana and cardamon litter which has higher C/N ratio than Coffee was due to less content of Nitrogen which was also one of the macronutrients for crop since this nutrient was involving on crop photosynthetic activity (Azizah et al 2023;Rinady et al 2023).…”

“…Moreover, the total soil cellulolytic bacteria population was positively correlated with soil moisture, crown cover, total soil nitrogen, and litter thickness (Yuan et al 2015;Chen et al 2018). Litter serves as a source of energy for soil microbes, and its accumulation can increase organic matter content, which in turn increases C accumulation on the soil surface (Azizah et al 2023;Rinady et al 2023). The study also found that land use with high sunlight intensity and soil temperature could slow decomposition; microclimate differences, particularly soil moisture, significantly impacted litter decomposition (Lee et al 2014).…”

“…Agroforestry systems are vital in increasing agricultural production by improving soil fertility, retaining organic matter, and promoting nutrient cycling (Tsufac et al 2019). This system will accumulate a significant amount of organic matter in the form of litter on the soil surface (Rinady et al 2023;Garratt et al 2018). The plant litter decomposition rate depends on its quality, the physical and chemical environment, and decomposer organisms (Jugran and Tewari 2022).…”