Organic waste can be a source of environmental pollution if not managed properly. The organic waste transformed by Black Soldier Fly (BSF) larvae produces liquid biofertilizer (LB) containing nutrients and beneficial microbes for plants. This study aims to determine the effect of dosage and frequency of application of liquid biofertilizer on the growth of cocoa seedlings and soil properties. The experiment used a randomized complete block design with seven treatments and four replications. The treatments were a control, LB 3% every two weeks, LB 3% every four weeks, LB 6% every two weeks, LB 6% every four weeks, LB 12% every two weeks, LB 12% every four weeks. The results showed that LB 6% every four weeks was the best treatment in increasing seedling height, stem diameter, and weight of fresh shoot, dry shoot, and dry roots of cocoa seedlings at 20 weeks old compared to other treatment. The application of LB significantly increased soil pH, but not significantly affected on the content of organic C, total N, available P and exchangeable cations at soil. Biofertilizer from bioconversion of organic waste using BSF larvae is suitable to improve the growth of cocoa seedlings.

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Corynespora causes leaf fall disease in rubber plants. Control can be done with bio fungicides and potassium fertilizer. This study aims to determine the effectiveness of essential oils and potassium fertilizer in controlling rubber leaf fall disease. The research was conducted from January to December 2018 in Landak Regency, West Kalimantan. The study used a randomized block design with 13 treatments repeated 3 times. The treatment is without biofungicide and KCl, citronella oil + (KCl 250 g, 312.5 g, and KCl 375 g), clove oil + (KCl 250 g, 312.5 g, and 375 g), liquid smoke + (KCl 250 g, 312.5 g, and 375 g), chemical fungicides (mancozeb) + (KCl 250 g, 312.5 g, and 375 g). The results showed that citronella oil, clove oil, and liquid smoke had the same inhibitory power as chemical fungicides. The combination of citronella oil with fertilizer KCl 312.5 g/plant/year and clove oil with KCl 375 g/plant/year can reduce the intensity of Corynospora attack up to 7.33% with inhibition of rubber leaf fall disease reaching 90.09% and can maintain yield of 28.1-28.3 g/tapping (94.33%). KCl fertilizer increased the lignin content of rubber leaves by 22.63%.

The growth of macadamia seedlings takes ± 1 year to become rootstock or planted in the garden. Acceleration of seedling growth can be accelerated through NPK fertilization by a watering system. The advantage of the watering system is easy to apply and the response of the seeds is faster because the fertilizer is immediately absorbed by the roots and leaves. The study aimed to determine the application time of NPK fertilization with the best watering system for the growth of macadamia seedlings. The experiment was carried out in a greenhouse at Indonesian Industrial and Beverages Crops Research Institutes(IIBCRI) Sukabumi Regency West Java, from September 2020 to February 2021. The study was conducted by a randomized block design with 5 treatments (application times of NPK fertilizer by watering). Types of treatments are : (P1) once a week, (P2) every 2 weeks, (P3) every 3 weeks, (P4) 4 weeks, and (P0) watering without fertilizer once a week. The experimental results showed that watering NPK fertilizer intervals of 2 weeks were the best treatment for the growth of macadamia seedlings with a height of up to 16 cm, a number of leaves (13.2) strands, root length of 19.82 cm, and dry weight, a total of 8.01 and a root-shoot ratio of 3.77. The dose and application time of NPK fertilizer can be used as information for effective and efficient fertilization so that it can be recommended as balanced fertilization to support sustainable agriculture.