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Biochar is an alternative amendment for improving soil is to rehabilitate degraded land, especially dry land. In addition, biochar serves as a habitat for soil microbes that play an important role in the availability of nutrients for plants. The use of biofertilizers in agriculture is part of the support for sustainable agriculture because it is environmentally friendly. This study aimed to examine effect of application biochar and biofertilizers combination on chemical and biological properties of soil as well as growth and yield of maize in an up land, Pandeglang Regency. The experimental design in this study was a factorial completely randomized design with two factors. The first factor was biochar with 3 levels (0; 2.5; 5 tons ha-1 ) and the second factor was combination of biofertilizer (PHC) and NPK with 5 types (100% PHC, 100% NPK, 25% PHC + 75% NPK, 50% PHC + 50% NPK, and 75% PHC + 25% NPK). Each treatment was replicated 3 times so there were 45 experimental units. The results of this study showed that the application of biochar dose of 5 tons ha-1 (B2) significantly increased K-available in soil and plant height. The combination of 75% biofertilizer and 25% NPK (P4) significantly increased the population of N2- fixing bacteria and cellulolytic bacteria. The combination of biochar dose 2 with 100% NPK fertilizer (B2P1) is the best treatment combination in improving soil nutrient status. On the other hand, the combination of application of biochar dose 1 (2.5 ton ha-1 ) with 50:50 concentration of biofertilizer and NPK (B1P3) has the opportunity to support the growth and yield of maize. [ABSTRACT FROM AUTHOR]

ABSTRAK Potential of Hydrogen (pH) adalah salah satu parameter penting yang terdapat pada nutrisi tanaman hidroponik. Setiap tanaman memerlukan nutrisi dengan pH sesuai kebutuhannya, agar dapat tumbuh dengan baik. pH nutrisi akan berubah setiap saat, sehingga perlu sering dipantau. Terdapat kendala pada pH meter yang digunakan saat ini, misalnya perlu kalibrasi ulang jika digunakan lebih dari 24 Jam karena elektroda sensor pH rentan terhadap larutan yang diukurnya. Pada penelitian ini dirancang sebuah pH meter cerdas yang akan digunakan untuk mengukur nutrisi tanaman. Alat ukur ini mampu digunakan secara terus menerus selama lebih dari 24 jam. Sensor pH yang digunakan adalah FIT0348 dan ATMega8 sebagai unit kontrolernya. Proses pengujian terdiri dari 4 tahap. Berdasarkan hasil pengujian, disimpulkan bahwa koefisien determinasi pada rangkaian pengkondisi sinyal yang dirancang telah linier yaitu 0,9999 dengan persamaan regresi y=0,0065x+6,189. ΔpH dari pH meter yang dirancang adalah ±0,01 dengan menggunakan PH/EC-9853 sebagai alat ukur pembandingnya. Kata kunci: potensial of hydrogen, pH meter, hidroponik, nutrisi tanaman ABSTRACT Potential of Hydrogen (pH) is one of the important parameters found in hydroponic plant nutrition. Every plant needs nutrients with pH according to their needs, so they can grow well. The pH of nutrients will change at any time, so it needs to be monitored frequently. There is a problem with the pH meter used today, for example, it needs recalibration if it is used more than 24 hours because the pH sensor electrode is susceptible to the solution it measures. In this study, a smart pH meter was designed to be used to measure plant nutrient. This measuring instrument can be used continuously for more than 24 hours. The pH sensor used is FIT0348 and ATMega8 as the controller unit. The testing process consists of 4 steps. Based on tests, it was concluded that the coefficient of determination in the signal conditioning circuit designed was equal to 0.9999 with the regression equation y = 0.0065x + 6.189. ΔpH from the pH meter designed is ± 0.01 by using PH/EC-9853 as a comparison measuring instrument. Keywords: potensial of hydrogen, pH meter, hydroponic, plant nutrition