Soil Micromorphologic Features of Holocene Surface Weathering and a Possible Late Quaternary Buried Soil, Northwest Arkansas

Micromorphologic features of an alfisol developed in White River alluvium near Fayetteville, Arkansas are typical for this soil order. The A horizon has a relatively high organic matter content and an abundance of quartz sand grains with a silt and clay matrix. Voids are relatively common and some have been partly infilled. In contrast to the A horizon, the E horizon has less organic matter, larger voids, and some weak orientation of the clay matrix. The parent material for these horizons was deposited in the past 4,700 years and these pedologic horizons have formed since that time. In the underlying B horizon clay has accumulated in the form of grain coatings and caps and as void linings. Translocation of clay into this horizon has relatively decreased the abundance of matrix silt and clay, and the amount of void space. The clay matrix that remains has extensively become oriented and some of the void space that remains is planar in shape. Both these features are partly responsible for the subangular blocky structure of this horizon. Deposition of this parent material began more than 8,000 to 10,000 years ago and was complete by 4,700 years ago. Many of the soil features have formed since 4,700 BP as the soil surface accreted upward. The lower portion of the B horizon (2B) is developed in an older alluvial parent material, more than 10,000 years old. Some micromorphologic features suggest that the upper portion of this 2B horizon originally was an A/E horizon that has been modified after burial by subsequent weathering of the present ground soil. Some relict surface horizon features, such as relatively abundant voids, infilled vughs, and matrix, have persisted after burial. Other features characteristic of A horizons, such as organic matter, have been destroyed by oxidation. Many of the micromorphologic features in this 2B horizon have developed since burial, more than 10,000 years ago. Translocated clay features are abundant and partially mask the relict A/E horizon features. The lower part of the 2B horizon was a B horizon that continued to develop as a B horizon after burial. Translocated clay features are more abundant in this horizon than in the overlying relict A/E horizon

Meningkatkan Produksi Kacang Tanah Lahan Alfisol dengan Menanam Varietas Toleran

Di Indonesia sebagian besar kacang tanah ditanam di tanah Alfisol, dan sering dihadapkan pada masalah ketersediaan dan ketidak-seimbangan hara. Karakteristik alkalis tanah Alfisol sering menjadi kendala peningkatan produksi kacang tanah karena terjadinya kahat Fe. Tidak semua varietas yang sudah dilepas beradaptasi baik di lingkungan Alfisol alkalis, varietas rentan terhadap kadar Fe rendah akan menderita klorosis dan kehilangan hasil bisa mencapai lebih dari 40%. Sampaidengan tahun 2004, di Indonesia telah dilepas sedikitnya 29 varietas unggul kacang tanah dengan berbagai tipe dan karakter, tetapi belum dapat menjawab permasalahan untuk tanah Alfisol. Penggunaan varietas yang diketahui toleran Alfisol alkalis merupakan salah satu upaya untuk meningkatkan hasil. Balitkabi telah menghasilkan beberapa varietas kacang tanah baru seperti Kancil, Bison, Domba, dan Turangga yang diketahui mampu beradaptasi dengan baik. Di samping itu, beberapa galur harapan seperti K/PI 405132-90-B1-2-57, K/PI390595//K-90-B-54, ICGV 88252/LM-92-B-4, K/PI298115-90-B-16 dan ICGV 87055 ditengarai prospektif untuk lahan Alfisol. Kajian di beberapa lokasi menunjukkan bahwa penggunaan varietas/galur toleran meningkatkan hasil 25–52%, nyata lebih tinggi dibanding lokal setempat

Reaction products of ammonium nitrate phosphate fertilizers of varying water-soluble phosphorus content in different Indian soils

Studies were undertaken on the isolation and identification of reaction products of ammonium nitrate phosphate (ANP) fertilizers containing 30, 50 and 70 per cent water-soluble phosphorus (WSP) of total phosphorus in representative soils of the vertisol, oxisol, alfisol, entisol, mollisol and aridisol groups of India. ANP fertilizers were applied in solid form to soil, and reaction products formed at and around the site of ANP fertilizer placement were identified after six weeks incubation in moist soils by X-ray diffraction technique. DCPD (dicalcium phosphate dihydrate- CaHPO4 . 2H2O) was the major reaction product of ANP fertilizers containing 30 and 50 per cent WSP in vertisol, entisol, aridisol, mollisol, oxisol and alfisol, and of ANP containing 70 per cent WSP in vertisol, entisol, alfisol, aridisol and mollisol. DCP (dicalcium phosphate-CaHPO4) was detected with ANP of 30 and 50 per cent WSP in the vertisol, alfisol, entisol, mollisol and aridisol groups of soils. In addition to DCPD, FePO4 . 2H2O (metastrengite) and AlPO4 . 2H2 O-monoclinic (metavariscite) were formed in alfisol and oxisol soils with ANP of 30 and 50 per cent WSP. FePO4 . 2H2O and AlPO4 . 2H2O (metavariscite) were identified in alfisol and oxisol soils while AlPO4 . 2H2O-orthorhombic (variscite) was formed in alfisol soils with ANP of 70 per cent WSP

Priming effects on labile and stable soil organic carbon decomposition: Pulse dynamics over two years.

Soil organic carbon (SOC) is a major component in the global carbon cycle. Yet how input of plant litter may influence the loss of SOC through a phenomenon called priming effect remains highly uncertain. Most published results about the priming effect came from short-term investigations for a few weeks or at the most for a few months in duration. The priming effect has not been studied at the annual time scale. In this study for 815 days, we investigated the priming effect of added maize leaves on SOC decomposition of two soil types and two treatments (bare fallow for 23 years, and adjacent old-field, represent stable and relatively labile SOC, respectively) of SOC stabilities within each soil type, using a natural 13C-isotope method. Results showed that the variation of the priming effect through time had three distinctive phases for all soils: (1) a strong negative priming phase during the first period (≈0-90 days); (2) a pulse of positive priming phase in the middle (≈70-160 and 140-350 days for soils from Hailun and Shenyang stations, respectively); and (3) a relatively stabilized phase of priming during the last stage of the incubation (>160 days and >350 days for soils from Hailun and Shenyang stations, respectively). Because of major differences in soil properties, the two soil types produced different cumulative priming effects at the end of the experiment, a positive priming effect of 3-7% for the Mollisol and a negative priming effect of 4-8% for the Alfisol. Although soil types and measurement times modulated most of the variability of the priming effect, relative SOC stabilities also influenced the priming effect for a particular soil type and at a particular dynamic phase. The stable SOC from the bare fallow treatment tended to produce a narrower variability during the first phase of negative priming and also during the second phase of positive priming. Averaged over the entire experiment, the stable SOC (i.e., the bare fallow) was at least as responsive to priming as the relatively labile SOC (i.e., the old-field) if not more responsive. The annual time scale of our experiment allowed us to demonstrate the three distinctive phases of the priming effect. Our results highlight the importance of studying the priming effect by investigating the temporal dynamics over longer time scales

Evaluasi keharaan alfisol dan peningkatan produktivitasnya untuk kacang tanah=Nutrient evaluation of alfisol and the productivity increment for groundnut.

Soil fertility evaluation is important in determining yield constrains and fertilizer efficiency. Thi research was conducted in 1998/1999 by analyzing Alfisols samples taken from groundnut production centers covering 9 and 6 districts in East and Central Java Provinces, respectively. In addition, a po experiment was also conducted to test the response of groundnut to N, P, K, and S fertilization. The objecav4 WaS to gel nutrient information in Alfisols in groundnut producing centers in East and Central Java, and al alternative of nutrient management to increase soil productivity. The results of the research showed that th4 majority of ,4Ifisols â¢om East Java had higher pH (varied from 7.0 to 8.4) than that from Central Javc (varied from 5.0 to 6.9). The variability of soil pH and Fe availability correlated significantly with th< groundnut productivity. The availability of Fe, Zn, Mn, and Cu in Alfisol from Central Java were high, Int the balance between Fe and the other ones, low soil pH, low available Ca and P might cause a log groundnut productivity. Phosphorus deficiency in Alfisol from East Java mainly took place in soil havin1 high soil pH and high exchangeable Ca. Nitrogen and phosphorus fertilization in the majority (60%) o thyland Alfisol from both area could increase groundnut productivity by over 50%. Keywords.- nutrient availability, Alfisol, groundnut, soil fertility. Evaluasi kesuburan tanah penting artinya untuk mengetahui kendala peningkatan produksi dar efisiensi pernupukan. Penelitian dilaksanakan pada MT 1998/1999 dengan melakukan analisis canto!, Canal Alfisol dart beberapa lokasi di sentra produksi kacang tanah yang meliputi 9 kabupaten di Jawa Timur clan [ kabupaten di Jawa Tengah. Di samping itu juga di]akukan percobaan pot, yang dibatasi hanya untuk menguj respon kacang tanah terhadap pemupukan N, P, K dan S. Tujuan penelitian adalah untuk mendapatkal infortnasi keharaan tanah Alfisol di sentra produksi kacang tanah di Jawa Timur dan Jawa Tengah, serf: alternative pengelolaan hara untuk meningkatkan produktivitasnya. Vasil pene]itian menunjukkan bahw mayoritas tanah Alfisol asal Jawa Timur tnempunyai pH lebih tinggi (7-8,4) dibandingkan Alfisol asal JawTengah (5-6,9). Variasi pH tanah dan tingkat ketersediaan Fe berkorelasi nyata dengan produktivitas kacang tanah. Ketersediaan unsur mikro Fe, Zn, Mn, dan Cu pada Alfisol asal Jawa Tengah cukup tinggi, namut keberimbangan unsur Fe dengan unsur mikro [ainnya, rendahnya pH, Ca, dan P tersedia diduga menjad penyebab rendahnya produktivitas kacang tanah. Kekahatan unsur P pada Alfisol Jawa Timur terutamterjadi pada tanah yang mempunyai p11 tinggi dan kandungan Ca-dd tinggi. Pemupukan N dan P di sebagiai besar (60%) lahan kering tanah Alfisol asal Jawa Timur dan Jawa Tengah dapat meningkatkan produktivuta kacang tanah >50% dibandingkan jika tanpa dipupuk. Kata kunci: keharaan, Alfisol, kacang tanah, kesuburan tanah

Geology, geohydrology, and soils of NASA, Kennedy Space Center: A review

Sediments underlying Kennedy Space Center (KSC) have accumulated in alternating periods of deposition and erosion since the Eocene. Surface sediments are of Pleistocene and Recent ages. Fluctuating sea levels with the alternating glacial-interglacial cycles have shaped the formation of the barrier island. Merritt Island is an older landscape whose formation may have begun as much as 240,000 years ago, although most of the surface sediments are not that old. Cape Canaveral probably dates from less than 7,000 years B.P. (before present) as does the barrier strip separating Mosquito Lagoon from the Atlantic Ocean. Merritt Island and Cape Canaveral have been shaped by progradational processes but not continuously so, while the Mosquito Lagoon barrier has been migrating landward. Deep acquifers beneath KSC are recharged inland but are highly mineralized in the coastal region and interact little with surface vegetation. The Surficial acquifer has formed in the Pleistocene and Recent deposits and is recharged by local rainfall. Sand ridges in the center of Merritt Island are important to its recharge

Microscopic observations of the recent soils: a step for understanding the paleosols

The microscopic observations of the recent soil horizons were conducted in Okayama, Japan (moderate climate). The several soil horizons, including two surface (epipedon) and three subsurface horizons, were recognized in the forest, poorly vegetated hill, and riverside around the Okayama University. The umbric epipedon can be segregated from the organic-rich subsurface horizons by the scattered organic materials in thin sections. The ochrich epipedon shows the sandy matrix without any cements and the illuviation of clay minerals. The subsurface horizons identified in the study area are as follows: albic, argillic, and cambic horizons. Each subsurface horizon shows the specific structures in thin sections. The albic horizon is characterized by the absence of the illuviation. The argillic horizon definitely shows the clayey matrix and the illuviation of clay minerals. The primary structures may be retained in the cambic horizon. The microscopic examination of the Miocene paleosols from the Ukan-cho, Okayama, was attempted. By comparing the recent soils, the cambic horizon and spodic horizon, which is characterized by the concentration of sesquioxides, are identified in the paleosols. This attempt suggests that the microscopic observations of the recent soils is a useful guide to understanding the paleosol

Soil organic carbon dynamics of improved fallow-maize rotation systems under conventional and no-tillage in Central Zimbabwe

Fallowing increases soil organic carbon (SOC) during the fallowing phase. However, this benefit is lost quickly during the cropping phase. The objective of this study was to evaluate SOC dynamics of an improved fallow-maize rotation under no-tillage (NT) and conventional tillage (CT) from time of fallow termination, through the next two cropping seasons. The treatments studied were improved fallows of Acacia angustissima (A. angustissima) and Sesbania sesban (S. sesban), natural fallow and continuous maize. Our hypothesis is that fallowing maintained higher SOC and lower soil bulk densities through the cropping phase when compared with continuous maize system and that NT maintained higher SOC when compared with CT. Soil organic carbon was significantly greater under fallows than under continuous maize from fallow termination to the end of the second cropping season. Soil organic carbon for the 0¿5 cm depths was 11.0, 10.0, 9.4 and 6.6 g kg¿1 for A. angustissima, S. sesban, natural fallow and continuous maize, respectively at fallow termination. After two cropping seasons SOC for the same depth was 8.0, 7.0, 6.1, 5.9 g kg¿1 under CT and 9.1, 9.0, 8.0, 6.0 g kg¿1 under NT for A. angustissima, S. sesban, natural fallow and continuous maize, respectively. Total SOC stocks were also higher under fallows when compared with continuous maize at fallow termination and after two cropping seasons. Soil bulk densities were lower under fallows when compared with continuous maize during the period of study. We concluded that fallows maintained greater SOC and NT sequestered more SOC than CT. Acacia angustissima was the better tree legume fallow for SOC sequestration when compared with S. sesban or natural fallow because it maintained higher SOC and lower bulk densities after two seasons of maize cropping

Late Pliocene lakes and soils: a global data set for the analysis of climate feedbacks in a warmer world

The global distribution of late Pliocene soils and lakes has been reconstructed using a synthesis of geological data. These reconstructions are then used as boundary conditions for the Hadley Centre General Circulation Model (HadCM3) and the BIOME4 mechanistic vegetation model. By combining our novel soil and lake reconstructions with a fully coupled climate model we are able to explore the feedbacks of soils and lakes on the climate of the late Pliocene. Our experiments reveal regionally confined changes of local climate and vegetation in response to the new boundary conditions. The addition of late Pliocene soils has the largest influence on surface air temperatures, with notable increases in Australia, the southern part of northern Africa and in Asia. The inclusion of late Pliocene lakes increases precipitation in central Africa and at the locations of lakes in the Northern Hemisphere. When combined, the feedbacks on climate from late Pliocene lakes and soils improve the data to model fit in western North America and the southern part of northern Africa