Fracionamento das Formas de Fósforo em Terra Preta de Índio / Phosphorus Fractionation on “Terra Preta de Índio”

A Terra Preta de Índio (TPI) é rica em fósforo (P) e cálcio (Ca), por ser um solo de origem antrópica. A forma de P inorgânico mais comum nesse solo, é aquela formada com Ca, consequência da mineralização da hidroxiapatita da composição de ossos de animais descartado no solo. Para entender o processo de extração de P em TPI, como os extratores químicos, foi realizado um estudo do fracionamento das formas de P inorgânicas, em conjunto com os extratores Mehlich-1 (M1), Mehlich-3, Bray-1 (B1) e Olsen (OL), com objetivo de verificar o comportamento de extração das principais formas do P inorgânico pelos extratores M1, M3, B1 e OL. E para tanto, as amostras de solo coletadas na profundidade 0-20 cm, em oito sítios da Mesorregião do Centro Amazonense foram submetidas ao fracionamento de P pelo método proposto por Chang e Jackson em consorcio das extrações com M1, M3, B1 e OL. Os resultados das partições das formas de P foram caracterizados pela variação de todas as formas, de acordo com local amostrado. O extrator M1 retirou quantidades variadas de P-FL, P-Fe e P-Al, e influenciou principalmente na retirada do P-Ca. O OL possui a extrai preferencialmente o P mais disponível para a solução do solo. Portanto, a dinâmica de extração de P com o M1, M3, B1 e OL, está diretamente relacionada com a variabilidade dos teores das formas de P-FL, P-Fe e P-Al e P-Ca em solos antrópicos.

POSISI CONTOH DAUN UNTUK ANALISIS STATUS FOSFOR (P) PADA BIBIT JARAK PAGAR (Jatropha curcas L.) DAN KADAR P TERSEDIA PADA DAERAH PERAKARANNYA

<p>ABSTRAK<br />Status P pada tanaman dapat diduga dengan menganalisis kadar P<br />pada daun, karena daun merupakan suatu bagian tanaman yang sangat<br />aktif. Untuk itu, diperlukan informasi posisi daun yang sesuai untuk<br />dijadikan contoh daun untuk analisis status P tanaman. Percobaan ini<br />bertujuan untuk menentukan posisi daun yang sesuai untuk analisis status<br />P dan mempelajari perbedaan antara kadar P tersedia di tanah dan di<br />rhizosphere, serta hubungannya dengan kadar P daun bibit jarak pagar.<br />Percobaan dilakukan di rumah kaca Balai Penelitian Tanaman Rempah<br />dan Aneka Tanaman Industri (Balittri) Pakuwon, Sukabumi, Jawa Barat,<br />pada September 2006 sampai dengan Juli 2007, disusun dalam rancangan<br />acak lengkap (RAL) dengan 3 (tiga) ulangan. Setiap unit percobaan terdiri<br />atas 20 tanaman. Perlakuan yang diuji adalah: (a) daun ke-1 atau daun<br />yang terletak tepat di bawah kuncup daun yang belum mekar sempurna,<br />(b) daun ke-2 atau daun yang terletak setelah/di bawah daun ke-1, (c) daun<br />ke-3, dan (d) daun ke-4. Parameter yang diamati adalah kadar P daun (%),<br />kadar P tersedia di tanah dan rhizosphere yang diukur dengan metode<br />Bray-1 P. Hasil penelitian menunjukkan bahwa daun ke-2 adalah posisi<br />daun yang sesuai sebagai contoh daun untuk analisis status P pada bibit<br />jarak pagar (Jatropha curcas L.). Kadar P di rhizosphere lebih rendah<br />daripada kadar P di tanah (Bray-1P) yang jauh dari akar jarak pagar. Pada<br />daun ke-2, keeratan hubungan yang ditunjukkan oleh koefisien regresi (R2)<br />antara kadar Bray-1 P di rhizosphere dan kadar P daun jarak pagar (R2 =<br />0.394) lebih tinggi daripada hubungan antara kadar Bray-1 P di tanah dan<br />kadar P daun (R2 = 0.371), sehingga untuk keperluan menggambarkan<br />ketersediaan P tanah atau untuk melihat hubungan P tanah tersedia dengan<br />kadar ataupun serapan P tanaman jarak pagar, akan lebih tepat bila contoh<br />tanah yang diambil berasal dari rhizosphere akar tanaman.<br />Kata kunci: Jarak pagar (Jatropha curcas L.), posisi daun, status P, P<br />tanah tersedia</p><p>ABSTRACT<br />Determination of leaf sample position for analysis of P<br />status in physic nut (Jatropha curcas L.) seedlings and<br />the available P in the root zone<br />Status of P in plants can be quantified by analyzing concentrations<br />of the nutrient in leaf as the leaf is the most active plant part. For this,<br />information on appropriate leaf position as samples for analysis of P status<br />in the plants is needed. A research was conducted with aims to determine<br />an appropriate leaf position of physic nut seedlings and to study<br />differences between the concentrations of available P (Bray-1 P) in the<br />bulk soil and the rhizosphere, along with their relationships with the<br />concentrations of leaf P. The experiment was carried out in a glasshouse of<br />Indonesian Spices and Other Industrial Crops Research Institute,<br />Sukabumi, West Java, from September 2006 to July 2007. The experiment<br />was arranged in a completely randomized design with three replications.<br />Each experimental unit consisted of 20 plants. The treatments were: (a) 1st<br />leaf or a leaf located exactly below the shoot, (b) 2nd leaf or a leaf located<br />below the 1st leaf, (c) 3rd leaf, and (d) 4th leaf. All the leaves were taken<br />from the primary branch of the plants. Parameters measured were P<br />concentrations in the leaf, P concentrations in the bulk soil and the<br />rhizosphere (Bray-1 P). The results showed that the 2nd leaf position was<br />the appropriate leaf position to be taken as samples for the leaf analysis of<br />P status in physic nut (Jatropha curcas L.) seedlings. The concentrations<br />of Bray-1 P in the rhizosphere were lower than that in the bulk soil, which<br />is further away from the roots. The R2 values for the relationships between<br />the Bray-1 P concentrations in the rhizosphere and the the 2nd leaf P<br />concentrations were higher than that between the Bray-1 P concentrations<br />in the bulk soil and the 2nd leaf P concentrations, hence, for the objectives<br />to show the soil P availability or to show the relationships between the<br />available soil P and the concentrations or the P uptake by the physic nut, it<br />will be more accurate if the soil samples are taken from the rhizosphere.<br />Key words: Physic nut (Jatropha curcas L.), leaf position, P status,<br />available soil P</p>

Reducing Phosphorus Fertilizer Input in High Phosphorus Soils for Sustainable Agriculture in the Mekong Delta, Vietnam

High rates of phosphorus (P) currently being applied to soils for the production of vegetables in the Mekong Delta, Vietnam, has led to concern regarding negative effects on the economy and the environment. This research presents a comprehensive study on the determination of P supplying capacity in this region of Vietnam to examine the possibility of reducing P fertilizer input. In total, 120 soil samples were collected to evaluate total P and Bray 1 available P in the soils. Phosphorus maximum sorption, degree of P saturation, P release, and the effect of P fertilizer on corn (Zea mays L.) yield in greenhouses and fields were also determined. Total P concentrations in 57% of the soil samples evaluated yielded high P concentrations (>560 mg P/kg), while 74% of the samples had high Bray 1 available P concentrations (>20 mg P/kg soil). Maximum P sorption ranged from 149 to 555 mg P/kg soil, respectively, and had negative correlation with available P (r = −0.63*). The percentages of P saturation ranged from 0.63% to 5.5% and correlated with available P (r = 0.98**). Maximum P release ranged from 1.2 to 62 mg P/kg soil, respectively, and correlated with available P (r = 0.96**). Corn grown in soils with available P concentrations >15 mg P/kg did not respond to P fertilizer in greenhouse or field experiments. We conclude that many farmers in this region can reduce P fertilizer input, thus increasing their profits and reducing negative environmental impacts associated with excess soil P for sustainable agriculture.

Critical Level Determination of Phosphorus for Big Red Chili (Capsicum annuum L.) Growth on Soil in Java Island

One of the efforts that can be done so that the fertilization of phosphorus (P) accommodate the P needs of big red chili is by conducting soil analysis and determine the critical level of P in the soil related to the yield. The objective of this research was to determine the critical level of P for big red chili in Java Island. Soil samples were collected from 19 locations in Java Island. The soil P before planting of 19 locations was determined by three methods of P extraction namely Bray 1, Olsen, and Mehlich III. After soil P analyses, big red chili was planted in a pot containing 500 g of soil (oven-dry weight) from 19 locations where each location had 4 rates of P fertilization. The rates of P fertilization applied were 0, 55, 110, and 220 kg ha-1 P2O5. Urea and KCl were applied with the rate of 110 kg ha-1 and 180 kg ha-1 respectively as basal fertilizers. Plant biomass was harvested after the age of 4 weeks after planting. The effect of P fertilizer on growth parameters was evaluated using analysis of variance. The critical level of soil P was determined by the Cate and Nelson method. The results showed that P fertilization had a significant effect on plant height, fresh weight and dry weight of plants. Fertilization treatment of 220 kg ha-1 P2O5 resulted in the highest responses to plant growth parameters. The correlation test results showed that Bray 1, Olsen and Mehlich III extraction methods significantly and positively correlated with plant dry weight. The Olsen extraction method showed the highest correlation with plant dry weight (r=0.665). The critical levels of P in the soil for big red chili in Java determined by Bray 1, Olsen, and Mehlich III extraction methods, were 15 ppm, 40 ppm, and 50 ppm, respectively. Keywords: Bray 1, Cate and Nelson, extraction method, Mehlich, Olsen, soil analysis

Penetapan Metode Ekstraksi Kalium Terbaik untuk Tanaman Tomat (Solanum lycopersicum L.) pada Tanah Andisol

Penetapan rekomendasi dosis kalium (K) berdasarkan uji tanah untuk tanaman tomat pada tanah Andisol belum banyak dikaji di Indonesia. Penelitian diawali dengan pembuatan status hara K tanah di Kebun Percobaan IPB Pasirsarongge Cianjur dilanjutkan dengan uji korelasi di rumah plastik PKHT IPB Tajur Bogor pada Desember 2015 sampai Mei 2016. Tujuan penelitian adalah menetapkan metode ekstraksi K terbaik bagi tanaman tomat di tanah Andisol. Status K tanah dibuat dengan larutan kalium sulfat (K2SO4) sebesar 0, ¼X, ½X, ¾X, dan X dimana X adalah 413.4 kg K ha-1 sebagai dosis K maksimum yang ditambahkan untuk mencapai kadar K maksimum dalam larutan tanah. Larutan K2SO4 disiram merata pada bedengan tanah dan diinkubasi selama 4 bulan. Ekstraksi K tanah menggunakan 5 metode yaitu: Bray 1 (HCl 5N), HCl 25%, Morgan Wolf (NaC2H3O2.3H2O), Mechlich (HCl 0.05N + H2SO4 0.025N) dan NH4OAc (NH4OAc, pH 7). Hasil penelitian menunjukkan adanya perbedaan respon tinggi tanaman, bobot kering biomas, kandungan K tanaman terhadap tingkat status hara K tanah. Pola respon kuadratik ditunjukkan pada tinggi tanaman umur 6 dan 7 minggu setelah tanam, dan bobot kering total. Metode ekstraksi K Andisols terbaik untuk tomat adalah NH4OAc dengan nilai koefisien korelasi (r): 0.75. Kata kunci: biomas, K2SO4, metode ekstraksi, NH4Oac, status K

Influence of Fertilization on Maize in Different Nutrient Classes on Jeneponto and Gowa District, South Sulawesi Regency, Indonesia

The field experiment was conducted on dry land in two location, that Jeneponto district and Gowa district, South Sulawesi regency by using single location approach. The aims of this research are (1) to determine the critical values of N, P and K for maize, and (2) to determine the rate of fertilizer on maize in the different classes of soil nutrient. Treatments were arrangement as a split-plot in randomized complete block design with three replications. Main plot were soil nutrient classes (low, moderate and high of N, P and K) and subplot were the rate of fertilizer of N, P and K. The results indicated that the critical values of total soil nitrogen for maize on Entisols (Thypic Ustorthents), Inceptisols (Oxic Haplustepts) and Vertisols (Typic Haplusterts) by using Cate-Nelson Method are 0.15, 0.15 and 0.11% N, respectively. Thus, the critical values of P and K for maize on Alfisols (Typic Rhodustalfs) are 0.32 ppm P, 85 mg P/100 g, 0.42 ppm P and 1.04 ppm P for each Mechlish, HCl 25 %, Bray-1 and Bray-2 extraction, respectively. 0.37 me K 100 g-1, 0.55 me K 100/g, 178 ppm P, 213 ppm P for each NH4OAc pH 4.8, NH4OAc pH 7, Bray-1 and Olsen extractions, respectively. Rate of nitrogen fertilizer on Entisols, Inceptisols and Vertisols soil in Jeneponto district which gave the highest maize yield reached of fertilizer 180 kg N/ha for low class, 120 - 180 kg N/ha for moderate class, and 60 - 120 kg N/ha for high class of N total, while the rate of P fertlizer for the low and moderate P class of 160 kg P/haand 40-80 kg P/ha for high P class. While the rate fertilizer of K for low K class of 80 – 160 kg K/ha, moderate K class of 40 – 80 kg K/ha, and high K class of 20 – 40 kg K/ ha on Alfisols soil in Gowa district.

Morphological Performance of Bangka Local Cassava on Acid Soils with The Addition of Mycorrhiza

The local cassava plant of Bangka has not been utilized optimally because its production is still low compared to national varieties. There are several ways to create good soil conditions to support plant growth in acid soils, such as the addition of mycorrhiza. The objective of the study was to increase the growth and production of Bangka local cassava in acid soils. The experiment had been conducted on acid soils with pH 4.4 (very acidic) and P-Bray 1 5.8 ppm (very low) in Balunijuk Village, Bangka Regency, from September 2016 - May 2017. This research used the experiment method with factorial randomized block design (FRBD) with two factors. The first factor was Bangka local cassava namely Sutera, Mentega, Batin, 3 Bulan and Malang variety (as the comparison) and second factor was mycorrhiza. The results showed Sutera accession had the highest plant height and production in acid soils. The addition of mycorrhiza as much as 50 g / plant can increase the growth and production of Bangka local cassava. The Bangka local cassava showed better growth quality but still have lower production compared with national varieties. Conservation of local cassava plants Bangka in acid soils can be optimized its growth by using local clones Bangka, but the production of national varieties is higher compared local cassava of Bangka

Ascertainment of K Nutrient Availability Class for Maize by Several Methods

Research was conducted in Gowa, South Sulawesi at dry land farmer during two years. The aims of the research was to get the best method in ascertainment of availability class of potassium (K) for maize in dry land. The research used a single location approach, which made some of K nutrient artificial. Result of this research indicated that K nutrients class which reached by several methods are: (1) by Cate-Nelson method : two class, ie low and high class, (2) by curve continue method: two until three classes, ie very low to moderate class, low and moderate, and low to high class; and (3) by analysis of variance modified method: three classes, ie low to high class. Ascertainment of K nutrient availability classes by modified analysis of variance method was the best methods compared to other methods. Critical level of K nutrient for maize according to modified analysis of variance method by several extractant is: 0.40 me K 100 g-1 for NH4OAc pH 4.8 extractant; 0.40 to 0.60 me K 100 g-1 for NH4OAc pH 7 extractant; 200-300 ppm K2O for Bray-1 extractant, and 215-250 ppm K2O for Olsen extractant. [How to Cite: Marthen PS and P Tandisau. 2015. Ascertainment of K Nutrient Availability Class for Maize by Several Methods. J Trop Soils 19: 21-27. Doi: 10.5400/jts.2015.20.1.21][Permalink/DOI: www.dx.doi.org/10.5400/jts.2015.20.1.21]

Adubação fosfatada para cana-de-açúcar em solos representativos para o cultivo da espécie no Nordeste brasileiro

O objetivo deste trabalho foi avaliar a disponibilidade de P em solos representativos para o cultivo da cana-planta no Nordeste brasileiro, e estabelecer uma nova recomendação de adubação com o nutriente para a cultura nestes solos. O estudo foi realizado em cinco solos da Zona da Mata de Pernambuco: Argissolo Amarelo distrocoeso, Argissolo Amarelo distrófico, Latossolo Amarelo distrófico, Gleissolo Háplico eutrófico e Espodossolo Humilúvico órtico. Avaliaram-se sete doses de P, determinadas quanto à capacidade máxima de adsorção de P de cada solo (fósforo remanescente, P-rem). Aos 30 dias após a fertilização, os teores de P nos solos foram determinados com os extratores Mehlich-1, Mehlich-3, Bray-1 e resina de troca aniônica. Os níveis críticos de P foram calculados para cada solo e extrator. A partir dos intervalos de disponibilidade de P, foram definidas cinco classes de fertilidade para diferentes conteúdos de argila nos solos: muito baixa, baixa, média, alta e muito alta. Mehlich-1 e a resina de troca aniônica são os extratores capazes de representar adequadamente a disponibilidade P, para o cultivo de cana-planta nos solos avaliados.