Penggunaan pupuk silika telah mendapat perhatian dalam budi daya padi, namun kajian mengenai status hara tanah belum banyak dilaporkan di Indonesia. Dengan demikian, perlu dilakukan penelitian untuk menentukan status hara dan pengaruh pupuk silika pada produksi padi. Tujuan penelitian adalah untuk mempelajari pengaruh trass pada perubahan sifat kimia tanah, mengetahui respons padi pada pupuk silika dan menentukan status hara Si dengan metode Cate-Nelson dan kurva kontinu. Hasil menunjukkan bahwa pemberian trass memberikan pengaruh nyata pada sifat kimia tanah, seperti pH H2O dan Si tersedia. Status hara Si diukur dengan menggunakan beberapa ekstraktan berbeda, yaitu H2O; CaCl2; NH4OAc pH 4,8; dan Na-Asetat pH 4 memberikan nilai batas kritis 13,17, 34, dan 37 ppm, setara dengan 28 ppm, 36 ppm, 73 ppm, dan 79 ppm SiO2. Kelas ketersediaan hara kategori sedang berdasarkan metode kurva kontinu dengan ekstraktan H2O, 0,01 M CaCl2, NH4OAc pH 4,8, dan Na-OAc pH 4 berturutturut adalah 1834, 3341, 4479, dan 4281 mg SiO2 kg-1. Pemberian trass bakar dengan dosi 10 g kg-1 memberikan produksi beras tertinggi sebesar 44,19 g pot-1 setara dengan 7,07 ton ha-1 .

Labile organic carbon fraction (LOC) response as a sensitive indicator of changes in soil quality. Changes in land management, use, and land cover significantly affect the total soil organic carbon. Organic forms such as the labile carbon fraction are still very rarely studied and affect soil quality. Soil quality is defined as the soil’s capacity to perform various functions and can be accessed by measuring the physical, chemical, and biological properties of the soil. Organic carbon of various forces has a major role in soil function. It is important to know the labile fraction of soil carbon because this fraction is a food source and greatly affects the nutrient cycle and other soil properties.

<p>Polusi tanah merupakan masalah lingkungan yang sering dihadapi. Polusi tanah mengacu pada keberadaan bahan kimia atau zat atau hadir pada konsentrasi yang lebih tinggi dari batas normal serta memiliki dampak negatif pada makhluk hidup dan lingkungan. Sumber polusi tanah tentunya berasal dari kegiatan pertambangan, limbah rumah tangga, kegiatan pertanian dan masih banyak lagi. Apablia tidak dilakukan Tindakan pencegahan atau remediasi dapat memberikan dampak negative terhadap lingkungan terutama bagi Kesehatan manusia. Berbagai macam metode remediasi dapat dilakukan dengan metode berbasis sains seperti peningkatan aktivitas mikroba (Bioremediasi) dan Fitoremediasi dianggap dapat  menjadi teknik pengendalian tanah tercemar karena mudah dan ekonomis untuk dilakukan.</p>

Fertilizer is one of the determining factors for the success of potato cultivation. Various types of fertilizers have been produced, but those that are suitable for regional conditions in North Sulawesi do not yet exist. The decreasing of potato production in North Sulawesi is due to the limited use of quality and certified seeds, as well as inappropriate fertilizer dosages. This research objective was to see the effect of NPK fertilization on the production of Medians potato plants. The research was conducted from August to December 2020, in Rurukan Village, East Tomohon District, Tomohon City, North Sulawesi. The experimental design used was randomized complete block design (RCBD) with seven treatments, namely the NPK fertilizer dosage of 0 kg ha-1 (P0), 150 kg ha-1 (P1), 300 kg ha-1 (P2), 450 kg ha-1 (P3), 600 kg ha-1 (P4), 750 kg ha-1 (P5) and 900 kg ha-1 (P6). Each treatment was repeated three times and resulting in 21 treatment plots. The results showed that application of NPK fertilizer of 450 kg ha-1 resulted the highest yields on the components of weight of fresh plant, tuber diameter, and potato productivity.

<p>Zinc (Zn) is a micronutrient that has an important role in various physiological and photosynthetic processes of plants. However the important role of Zn has not yet been concidered. This paper discussed the source of Zn and its availability in the soil, the important role of Zn in plants and strategies to overcome Zn deficiency in the soil. Zn has an important role in increasing crop production and yield quality. Zn nutrients in soil derived from parent material with an average content of 78 mg/kg. The low Zn level in the soil causes stunted plant and low crop yields. Zinc deficiency in plants resulted leaf chlorosis, necrotic spots on leaves, stunted plants, deformed and stunted leaves. Zn deficiency in soil can cause yield loss up to 40% without the appearance of leaf symptoms. Plants absorb Zn in the form of Zn2+. Soils in Indonesia have low Zn content so that production and quality of crops are low. Zn plays an important role in plant growth, gene expression, enzyme structure, photosynthesis, pollen development, sugar transformation, protein synthesis, membrane permeability, signal transduction and auxin metabolism, and increasing maturation of seeds and stems. The critical limit of soil Zn for most plants ranges from 0.5-2.0 mg Zn/kg for DTPA extractant, while the critical limit in plant tissue is 20 mg Zn/kg. The management of Zn nutrients needs to be considered, although it is needed only in small amounts. Without Zn nutrient management, its concentration in soil will continuously decreased. Management strategies in overcoming low Zn availability in plants are application of fertilizer containing Zn and the use of varieties that have high Zn content. The application of ZnSO4 of 60 kg/ha can increased the yield of grain, straw, number of tillers, plant height and weight of 1000 grains in rice plants. The treatment of soaking rice seeds in a solution of 0.05% ZnSO4 for ± 5 minutes + 100 kg TSP/ha was the best treatment giving the highest grain weight in Grumusol and Alluvial.</p><p>Keywords: Micronutrients Zn, deficiency, management</p><p> </p><p><strong>Abtrak</strong></p><p>Hara mikro Zn memiliki peranan penting dalam berbagai proses fisiologis dan fotosintesis untuk meningkatkan pertumbuhan dan hasil tanaman, namun belum mendapatkan perhatian. Naskah ini membahas sumber Zn dan ketersediannnya pada tanah, peranan penting hara Zn pada tanaman, dan strategi mengatasi kekurangan Zn dalam tanah. Hara Zn dalam tanah berasal dari batuan bahan induk tanah dengan kandungan rata-rata 78 mg/kg. Kadar Zn yang rendah di tanah menyebabkan pertumbuhan tanaman terhambat dan hasil rendah. Kekurangan Zn pada tanaman menyebabkan klorosis dan bintik-bintik nekrotik pada daun, pertumbuhan kerdil, dan daun cacat. Pada tanah yang kekurangan Zn, tanaman dapat mengalami kehilangan hasil hingga 40% tanpa gejala pada daun. Tanaman menyerap Zn dalam bentuk Zn2+. Tanah di Indonesia memiliki kandungan Zn yang rendah sehingga produksi dan kualitas tanaman rendah. Zn berperan penting dalam pertumbuhan tanaman, ekspresi gen, struktur enzim, fotosintesis, perkembangan polen, transformasi gula, sintesis protein, permeabilitas membran, transduksi sinyal, metabolisme auksin, pematangan biji dan batang. Batas kritis Zn dalam tanah untuk sebagian besar tanaman berkisar antara 0,5-2,0 mg Zn/kg untuk pengekstrak DTPA, sedangkan batas kritis pada jaringan tanaman 20 mg Zn/kg. Meskipun diperlukan tanaman dalam jumlah yang kecil, hara Zn perlu dikelola dengan baik. Strategi pengelolaan hara Zn agar selalu tersedia di tanah adalah melalui pemupukan dan penggunaan varietas yang mengandung Zn tinggi. Pemberian ZnSO4 60 kg/ha dapat meningkatkan hasil gabah, jerami, jumlah anakan, tinggi tanaman, dan bobot 1.000 butir tanaman padi. Perlakuan perendaman bibit padi dalam larutan 0,05% ZnSO4 selama ± 5 menit + 100 kg TSP/ ha memberikan bobot gabah tertinggi pada Grumusol dan Aluvial.</p><p>Kata kunci: Hara mikro Zn, defisiensi, pengelolaan</p>