BIODIVERSITAS ISSN: 1412-033X Volume 24, Number 3, March 2023 E-ISSN: 2085-4722 Pages: 1333-1345 DOI: 10.13057/biodiv/d240302 The effect of land management and organic matter inputs on bacterial population and soil nutrients across different types of agroforestry system MAYDELLA VISTA PUTRI RINADY 1,♥ , YULIA NURAINI 2 , CAHYO PRAYOGO 2,♥♥ , NOVI ARFARITA 3 1 Graduate Program of Soil and Water Management, Faculty of Agriculture, Universitas Brawijaya. Jl. Veteran No. 1, Malang 65145, East Java, Indonesia. Tel./Fax.: +62-341-576273,  email: maydella57@gmail.com 2 Department of Soil Science, Faculty of Agriculture, Universitas Brawijaya. Jl. Veteran No. 1, Malang 65145, East Java, Indonesia. Tel./fax.: +62-341-553623,  email: c.prayogo@ub.ac.id 3 Program of Agrotechnology, Faculty of Agriculture, Universitas Islam Malang. Jl. Mayjen Haryono No. 193, Malang 65144, East Java, Indonesia Manuscript received: 23 December 2022. Revision accepted: 1 February 2023. 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 10 5 CFU/g and 4,24 x 10 4 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. Keywords: Agroforestry, land use change, organic matter inputs, soil bacteria Abbreviations: CMC: Carboxy Methyl Cellulose, TBP: Total Bacteria Population, TCB: Total Cellulolytic Bacteria, TPC: Total Place Count INTRODUCTION Agroforestry ecosystems have been recognized to accumulate high levels of organic matter (Garratt et al. 2018), including greater litter production at the soil surface (Muchane et al. 2020). Litter is one of the major organic materials closely linked to biogeochemical processes to incorporate carbon and other plant nutrients into the soil (Bradford et al. 2016). The decomposition of plant litter affects the microorganisms' population and activities since carbon is becoming the major source of energy (Osman 2013). The quantity and quality of litter determine the rate of decomposition processes (Rahmadaniarti and Mofu 2020). Factors influencing the litter decomposition rate are soil properties and environmental conditions such as soil temperature and moisture (Schneider et al. 2012). The soil environmental conditions were also impacted by different land management practices, which then those activities modify the accumulation of litter surface (Giweta 2020). Signors et al. (2018) examined the changes in soil nutrients (C, N, P, K, etc.) across different land use and management. Higher nutrient accumulation was detected under native vegetation than in pasture, annual crops, fruit trees, and horticulture (Signors et al. 2018). Vegetation types and land management are important factors in ecosystem sustainability to secure nutrient availability (Soleimani et al. 2019). The decomposition of plant residues is governed by microbial activity (Thoms and Gleixner 2013), and several available substrates are provided by different plantations for microbial growth, thereby providing different soil microbial functions (Jagadamma et al. 2014). The plant composition changes could affect microclimatic soil conditions (Gutiérrez and Vivoni 2013; Ivanov et al. 2018), such as soil temperature,