No abstract

Proses pembibitan ubijalar haruslah didukung dengan ketersediaan hara yang cukup agar mampu meningkatkan produksi bibit yang berkualitas. Penambahan pupuk kandang ayam dan senyawa humat mampu meningkatkan kesuburan tanah. Penelitian ini bertujuan mengetahui pengaruh aplikasi pupuk kandang ayam dan senyawa humat terhadap jumlah bibit ubi jalar dan kesuburan tanah. Penelitian dilakukan menggunakan Rancangan Acak Kelompok Faktorial dengan dua faktor yaitu faktor pupuk kandang ayam dan faktor senyawa humat. Variabel pengamatan meliputi variabel kuantitas bibit dan variabel kesuburan tanah. Variabel kuantitas bibit adalah jumlah cabang dan jumlah bibit stek yang dihasilkan sedangkan variabel kesuburan tanah meliputi C-organik, N-total, P-tersedia dan K tersedia. Hasil penelitian menunjukkan kombinasi pupuk kandang ayam dan senyawa humat berpengaruh terhadap peningkatan jumlah cabang, jumlah bibit stek yang dihasilkan, N-Total, P-tersedia dan K-tersedia yang terdapat di dalam tanah. Pemberian faktor tunggal pupuk kandang berpengaruh terhadap peningkatan C-organik tanah. Kombinasi terbaik dalam meningkatkan kualitas bibit dan kesuburan tanah yaitu A2P3 (senyawa humat 200 ml dan pupuk kandang ayam 60 gram/tanaman/5 kg tanah).

Lahan sub optimal merupakan lahan yang memiliki produktivitas rendah. Rendahnya hara menjadi faktor pembatas dalam pengembangan lahan kering menjadi wilayah pertanian. Nitrogen merupakan hara esensial yang sangat diperlukan tanaman. Penggunaan tanaman legum yang mampu bersimbiosis dengan bakteri penambat nitrogen dapat meningkatkan ketersediaan nitrogen dalam tanah. Penelitian ini bertujuan untuk mengetahui populasi bakteri penambat nitrogen dan hubunganya dengan ketersediaan nitrogen tanah pada beberapa lokasi budidaya lahan kering di Kabupaten Situbondo, Jawa Timur. Penelitian dilakukan di lahan budidaya kacang panjang (Vigna sinensis L.). Variabel yang diamati meliputi populasi bakteri penambat N2 (Rhizobium sp., Azotobacter sp., dan Azospirilium sp.), N-total, pH, C-organik dan rasio C/N. Hasil menunjukkan lahan budidaya di Kecamatan Banyuglugur memiliki populasi bakteri dan nilai Ntotal tertinggi dibandingkan dengan lahan lainnya. Populasi bakteri yang tinggi disebabkan karena kesesuaian ekosistem awalnya dengan media perbanyakan. Perbedaan lokasi penanaman tidak berpengaruh terhadap ketersediaan nitrogen tanah namun berpengaruh terhadap C-organik tanah.

Seed cutting of sweet potato influenced by nutrient availability, especially nitrogen. Humic straw substances and cattle chicken manure fertilizer can increase the amount of nitrogen in the soil and also can improve the physical nature of soil. This study aimed to find out the influence of humic straw substances and cattle chicken manure fertilizer application toward the uptake of nitrogen nutrients for the seeds cutting quality of sweet potatoes. This research was conducted using factorial Randomized Block Design (RBD) with two factors, trere are humic straw subtances and cattle chiken manure. The variable observed was pH, C-Organic, N-Total of soil total length of plants, wet weight, dry weight, content of N-tissue, and N absorption. The result showed that a combination of humic straw substances and cattle chicken manure fertilizer influence to the increase of N-Total of soil, N-tissue, the uptake of N, the total length of plant, wet weight, and dry weight of the upper plants. The addition of a single factor of chicken manure fertilizer affects to the increase of pH and C-Organic of soil. Moreover, the best treatment combination in increasing the nitrogen uptake were A2P3 treatment (with 0.2% humic acid and 0.92 gram N of manure fertilizer). Furthermore, the best treatment combination in improving the number of seedlings cutting of sweet potatoes was A0P1 treatment (without humic acid and adding 0.46 gram N of  manure fertilizer).  Keywords:  seed cutting of sweet potatoes, nitrogen, chiken cattle manure and humic subtances.

The use of intensive chemical inputs causes lower availability of nutrients, organic matter, cation exchange capacity, and soil degradation.Therefore, this study aims to assess the soil quality index (SQI) for paddy fields in Jember, East Java, Indonesia. Input data for this study consist of land cover (interpreted from the Sentinel-2 image), soil type, and slope maps. Furthermore, the procedure to calculate soil quality index (SQI) include (1) spatial analysis to create the land unit, (2) preparation of soil sampling, (3) soil chemical analysis, (4) principal component analysis (PCA), and (5) reclassifying soil quality index (SQI).  The PCA results showed that three variables i.e., % sand, total- P, and % silt were strongly correlated to SQI, while three classes namely very low, low, and medium of SQI were sufficiently used to describe the spatial variability of the paddy field. Furthermore, approximately 41.14% of the paddy field area were classed as very low while 52.23%, and 6.63% were categorized as low and medium SQI respectively. Based on the results, about 93.37% of paddy fields in Jember Regency still require improvement in soil quality via the addition of ameliorants such as organic fertilizers to increase quality and productivity. This application needs to focus on areas with very low-low quality hence, the quality increased to the medium category. Keywords : Mapping; Soil Quality Index (SQI); PCA; Paddy field Copyright (c) 2021 Geosfera Indonesia and Department of Geography Education, University of Jember This work is licensed under a Creative Commons Attribution-Share A like 4.0 International License