Pengaruh pengelolaan agroekosistem terhadap kelimpahan kutu loncat jeruk Diaphorina citri Kuwayama (Hemiptera: Liviidae)

Asian citrus psyllid (ACP) Diaphorina citri Kuwayama is a serious problem in citrus because it transmits huanglongbing (HLB) disease. Agricultural practices without paying attention to the agroecosystem complexity often cause the agroecosystem more suitable for insect pests proliferation and less friendly to natural enemies. The research aims to study the effectiveness of agroecosystem management compared to conventional farming in the ACP control. The effects of both treatments on the diversity and abundance of ACP’s natural enemies as well as the incidence and severity of HLB were also studied. Agroecosystem management consists of preventive and responsive actions. Preventive action was carried out through a polyculture system, planting refugia and legume cover crop, providing beetle banks, applying lime, applying organic and inorganic fertilizers, citrus pruning intensively, maintaining drainage ditches, and mechanical weed control. Responsive action is short-term control when the abundance of ACP reaches the action threshold. Responsive action was carried out through biological or chemical control. Meanwhile, conventional farming is a series of conventional farming and pest control techniques commonly applied by farmers. Each treatment was applied in three orchards of Siam Orange cv. Pontianak Citrus nobilis Lour var. microcarpa Hassk. The results showed that agroecosystem management was more effective in controlling the ACP population so that its abundance was lower and less fluctuated than conventional farming. ACP’s natural enemies in agroecosystem management were also more diverse than conventional farming. The abundance of ACP’s natural enemies and the incidence and severity of HLB in the two treatments were not significantly different.

Growth of Legume Cover Crops under Cassava and Its Effect on Soil Properties

Background: Low soil organic carbon is a constraint to cassava tuber formation. Some legume cover crops could be an alternative to provide organic matter on the cassava field as a source of soil organic carbon. The study was aimed to evaluate the growth of some legume cover crops under cassava and their effects on soil properties. Methods: During September 2017-July 2018 legume cover crops (Calopogonium mucunoides, Centrosema pubescens, Pueraria javanica and the mixed) were planted under cassava variety of Mangu and UJ-5. The land coverage by the legume cover crops was measured monthly from 2 to 10 months after planting. Cassava growth was observed weekly from 8 to 32 weeks after planting. Soil properties were analyzed before planting and at harvesting of cassava. Result: Pueraria javanica was tolerant toward cassava shading. The land coverage was linearly increased along with the growth of cassava. At the end of cassava growth, the land area coverage by this legume cover crop was 98.08%. It produced more organic matter and could maintain soil moisture content than other legume cover crops. P. javanica could consider being a suitable legume cover crop under cassava to improve soil quality.

EFEK IRADIASI SINAR GAMMA PADA TANAMAN KACANG PENUTUP TANAH (Mucuna bracteata L.)

Legume cover crop (Mucuna bracteata L.) is a creeper which is currently often used to increase soil fertility in plantation areas. This plant is a leguminous plant that can fix nitrogen nutrients in the soil. One of the M.bracteata plant breeding programs to increase diversity is mutation using gamma ray radiation. The research objective was to determine the level of radiosensitivity of legume cover crop using gamma ray irradiation. The research was conducted at PAIR BATAN using a Gamma Chamber 4000A irradiator and in agricultural experiment, Labuhanbatu University. The plant material used was M.bracteata seeds with irradiation doses of 0, 200, 250, 300, 350 and 400 Gy. This study uses a curve fit analysis program to calculate the LD50 value (Lethal dose 50). The results showed that the plant radiosensitivity by calculating the LD50 value of M.bracteata at the age of 2 Weeks After Planting) was 348.737 Gy. The higher the radiation dose given, the lower the percentage of growth. Key words: diversity; leguminous; lethal dosage; mutation; gamma rays

INDUKSI PEMBUNGAAN Mucuna bracteata MENGGUNAKAN PAKLOBUTRAZOL DENGAN SISTEM TANAM VERTIKAL

Mucuna bracteata one of Legume Cover Crop many used in plantation. Mucuna bracteata can not flowering naturally. The objective of this research is to induce flowering Mucuna bracteata through paclobutrazol treatment with verticulture system. The methods are : induce shortly vegetative fase,count of secondary adventif shoot, count rise of flower,count number of flower and number of flower induced. Design of this research is Random block design 1 factor 4 treatment and 3 replication. The concentration of paclobutrazol are 0, 400, 500, and 600 ppm. The result show paclobutrazol 600 ppm able to suppress growth of main spiraling shoot increased 13,32 cm. The average number of secondary spiraling shoot are 3,84; 3,66 and 3,33.

Soil aggregate stability increased with a self-regenerating legume cover crop in low-nitrogen, no-till agroecosystems of Saskatchewan, Canada

Black medic (Medicago lupulina L.) is a self-regenerating cover crop which was tested for its ability to improve soil physical properties. Soil aggregate stability was assessed in plots that included a black medic cover crop in a no-till grain rotation, which was fertilized with two levels of nitrogen (N), for 15 yr. In the wheat phase of the rotation, the medic cover crop increased mean weight diameter by 21% in the reduced N fertilizer treatment but not in the recommended N treatment. Generally, the addition of medic reduced the proportion of small aggregates and increased the proportion of large aggregates. This pattern was stronger in reduced N compared with recommended N fertilizer levels. This study provided evidence for medic to increase aggregate stability under low external N input grain production.

Legume Cover Crop Effects on Temperate Sugarcane Yields and Their Decomposition in Soil

Sugarcane is commercially produced on 340,000 ha in the US and is valued at over $1 billion US annually. Cultural practices that improve sugarcane sustainability are needed to maintain yields in fields with degraded soils. Historically, leguminous rotation crops provided organic matter and biologically fixed nitrogen (N) for subsequent sugarcane crops. Currently, sugarcane is usually grown as a monoculture with only a short, 6-month fallow period. The objective of these field studies was to determine how growing cowpea (Vigna unguiculata (L.) Walp.) and sunn hemp (Crotalaria juncea L.) as cover crops during fallow affected the yield of subsequent sugarcane crops. A companion laboratory study investigated the decomposition rate of cover crops in soil at different temperatures. Cowpea and sunn hemp production produced 12.8 t/ha dry matter and 250 kg N/ha. Cowpea generally improved plant cane yields, but the effects of sunn hemp varied. However, neither cowpea nor sunn hemp reduced cane or sucrose yields consistently, and mineral N additions may have a role in mitigating yield gains or losses. Based on laboratory data, the average half-life for cowpea and sunn hemp would be 3 months. Overall, using legume cover crops should be viewed as an important component of sustainable sugarcane practices.

PERANAN BAHAN/SISA ORGANIK LAIN SEBAGAI PENGGANTI TOP SOIL TEHADAP KEBERHASILAN REKLAMASI/REVEGETASI DI WILAYAH BEKAS TAMBANG BAUKSIT PT ANTAM Tbk UBP BAUKSIT KALIMANTAN BARAT1

ABSTRAK Top Soil masih memegang peranan penting untuk menunjang keberhasilan kegiatan reklamasi/revegetasi pada areal bekas tambang, khususnya pertambangan terbuka (open pit/cast). Lapisan/layer top soil yang relatif tipis/sedikit membuat kegiatan reklamasi/revegetasi menjadi tidak maksimal. Diperlukan bahan/sisa organik lain sebagai alternatif untuk menggantikan fungsi/peran top soil untuk memperbesar persentasi keberhasilan kegiatan reklamasi/revegetasi. Penelitian ini bertujuan untuk mengetahui sejauh mana peran dari bahan/sisa organik lain untuk membantu memperbaiki kualitas lahan di areal bekas tambang bauksit. Penelitian dilakukan dari mulai dari tahun 2017 sampai dengan tahun 2019, di areal reklamasi PT ANTAM Tbk UBP Bauksit, Kecamatan Tayan Hilir, Kabupaten Sanggau, Provinsi Kalimantan Barat. Metode yang digunakan adalah pembuatan dem plot ukuran 20m x 6m dengan kolom 1 (satu) sebagai kontrol (areal tanah asli/bekas tambang), kolom 2 (dua) untuk TKKS, Kolom 3(tiga) dengan Serasah, serta Kolom 4 (empat) dengan top soil. Keempat kolom tersebut untuk melihat sejauhmana tingkat pertumbuhan tanaman pokok (jambu hutan dan Jambu mete) dan Legume Cover Crop (LCC) dengan menggunakan perlakuan tersebut. Analisa sifat fisik kimia tanah juga dilakukan untuk mengetahui kandungan dari tiap-tiap bahan/sisa organik lain yang kemudian dibandingkan dengan top soil. Hasil penelitian menunjukkan bahwa bahan/sisa organik lain dapat memberikan konstribusi positif pada areal reklamasi/revegetasi, dengan meningkatkan percepatan pertumbuhan cover crop dan tanaman pokok. Hasil penelitian juga saat ini sudah diaplikasikan untuk kegiatan reklamasi/revegetasi PT ANTAM Tbk UBP Bauksit mulai dari tahun 2018 sampai dengan saat ini. Kata kunci : Top Soil, bahan/sisa organik lain, bekas tambang bauksit, open pit/cast, reklamasi, revegetasi, Jambu Hutan, Jambu Mete, LCC. ABSTRACT Top Soil still plays an important role to support the success of reclamation/revegetation activities in mine out areas, especially open pitcast mining. Top soil layers that are relatively thins/lightly make reclamation/revegetation activities not optimal. Other organic materials/waste is needed as an alternative to replace the function/role of top soil to increase the percentage of successful reclamation/revegetation activities. This study aims to determine the extent of the role of other organic materialswaste to help improve the quality of land mine out areas. The study was conducted from 2017 to 2019, in the reclamation area of PT ANTAM Tbk UBP Bauksit, Tayan Hilir District, Sanggau Regency, West Kalimantan Province. The method used is making a demonstration plot of 20m x 6m size with column 1 (one) as a control (original / mine out area), column 2 (two) for TKKS Treatment, Column 3 (three) for Serasah Treatment, and Column 4 (four) with top soil. The four columns are to see the extent of growth of staple plants (local guava and Cashew) and Legume Cover Crop (LCC) using these treatments. Analysis of soil chemical physical properties was also carried out to determine the content of each other organic material /waste which was then compared with top soil. The results showed that other organic materials/waste can make a positive contribution to the reclamation / revegetation area, by increasing the acceleration of cover crop growth and staple crops. The results of the study have also been applied for the reclamation/revegetation activities of PT ANTAM Tbk UBP Bauxite starting from 2018 until now. Keywords: Top Soil, other organic materials /waste, bauxite mining, mine out, open pit/cast, reclamation, revegetation, Local Guava, Guava, LCC, Cashew

BIOMASSA HIJAUAN Mucuna bracteata DAN PENGARUHNYA TERHADAP KADAR N TANAH DI PERKEBUNAN KELAPA SAWIT

Mucuna bracteata is one of the legume cover crop that is usually used in oil palm and rubber plantations. In general, legume cover crop are planted during the preparation / after land clearing when the oil palm are planted, Mucuna bracteata has covered the planting area. Mucuna bracteata growth conditions will affect soil biological properties, namely organic nutrient content, C/N balance, microbial population and macro-fauna activity. This study aimed to describe the soil and Mucuna bracteata plants in the phase of oil palm plants. The study was conducted in April - June 2019 in the area of ​​TBM 3 oil palm plantations in 2 locations, namely Pabatu Plantation and Tinjowan Plantation. Soil types in Pabatu Plantation are typic dystrudepts (Reddish Brown Podsolik) and in Tinjowan Plantation the type of soil is typic hapludults (Yellowish Red Podsolik) and some typic paleudults (Yellow Podsolik). This study used a descriptive design that describes the growth character / biomass of Mucuna bracteata on TBM 3 oil palm plantations. The results of this study are the fresh biomass of Mucuna bracteata in Pabatu Plantation is 43,260 kg / ha and Tinjowan Plantation is 34,146 kg / ha (79%) and dry biomass is 13,943 kg / ha in Pabatu Plantation and 12,705 kg / ha in Tinjowan Plantation. The levels of N leaves of Mucuna bracteata are in the high category. Soil organic matter content and total N in Pabatu and Tinjowan Plantation are in the low category.

PENGENDALIAN LAJU PERTUMBUHAN PUCUK TANAMAN PENUTUP TANAH Mucuna bracteata DC DENGAN Paclobutrazol Control of the Shoots Growth Rate of Land Cover Crop Mucuna bracteata DC with Paclobutrazol

ABSTRACTMucuna bracteata DC. is a species of legume cover crop that rapidly grow into the palm circles and climb and wind around the main trees and reduce the effectiveness and efficiency of plantation maintenance. These problems should be able to be controlled by slowing down the growth rate of M. bracteataby applied retardant such as paclobutrazol. This research was aimed to determine the level of concentration of the retardant and the growth suppression rate on M. bracteata. This research was conducted at the Teaching and Research Farm of Oil Palm Plantation of IPB, Singasari Village, District of Jonggol, Bogor Regency in February to May 2016. The application of paclobutrazol was done by spraying the retardant solution on the shoot of M. bracteata’s canopy. Paclobutrazol concentrations of 100 ppm and 200 ppm were treatments that significantly reduced rate of the growth of shoot and dry weight, compared to other treatments. The treatments of 100 ppm and 200 ppm, consequtively gave the suppression rate of 61.02% and 63.45 % and prolonged the rotation time of weeding, 141 and 156 days, compared to the control.Keyword : concentration, paclobutrazol, retardantABSTRACTMucuna bracteata DCadalah spesies kacang-kacangan penutup tanah yang sangat cepat bertumbuh memasuki piringan dan melilit tanaman utama dan mengurangi keefektifan dan efisiensi pemeliharaan. Permasalahan tersebut dapat diatasi dengan menekan laju pertumbuhan M. bracteata dengan pemberian zat penghambat tumbuh paclobutrazol. Penelitian ini bertujuan untuk mengetahui tingkat konsentrasi retardan dan tingkat penekanan pertumbuhan M. bracteata. Penelitian dilaksanakan di Kebun Pendidikan dan Penelitian Kelapa Sawit IPB, Singasari, Kecamatan Jonggol, Kabupaten Bobor pada bulan Januari hingga Mei 2016. Pengaplikasian paclobutrazol dilakukan dengan penyemprotan larutan retardan pada tajuk tanaman M. bracteata. Konsentrasi paclobutazol 100 ppm dan 200 ppm merupakan perlakuan yang mampu memperlambat pertumbuhan panjang sulur dan bobot kering M. bracteata.secara signifikan dibandingkan dengan perlakuan lain. Perlakuan 100 ppm dan 200 ppm bertutut-turut memberi tingkat penghambatan sebesar 61,02% dan 63,45% dan waktu rotasi 141 dan 156 hari, dibandingkan dengan kontrol.Kata kunci : konsentrasi, paclobutrazol, retardan