Grey-brown Soil Research Articles

KAJIAN DAERAH TERINTRUSI AIR LAUT DI WILAYAH PESISIR KECAMATAN KUTA UTARA, KABUPATEN BADUNG

The total population of District Kuta Utara 2014 recorded 68.422 people with an average population density of 2,021 people/km2 while the number of tourism accommodation facilities (hotels, villas, restaurants) recorded 399 pieces. The rapid of population growth and the development of tourism accommodation facilities require ground water more increasing. Intake of large amounts of ground water potential to cause pollution/ sea water intrusion. This study aims to determine the quality of the groundwater, knowing distribution maps sea water intrusion and to predict the level of sea water intrusion coming years. This research method uses descriptive quantitative method. Furthermore, to determine the quantity and quality of ground water was measured groundwater levels and analysis of the parameters of temperature, total dissolved solid, pH, chloride, hardness and electrical conductivity of the 60 sample wells. Results of analysis of each of the key parameters that can be mapped and known overlay distribution maps sea water intruded area. The observation of the quantity and quality of groundwater in coastal areas of Kuta Utara subdistrict shows the range of the depth of the ground water level between -5.15 meters to -22.16 meters. Results of the analysis of ground water quality of the 60 groundwater samples showed that there has been a decline in the quality of ground water is as much as 14 samples total dissolved solid (TDS) the highest reaches 1,122 mg/ l, the highest electrical conductivity reached 1,677 ìMhos / cm and the highest chloride reached 532, 5 mg/l. Distribution maps sea water intruded area shows that in coastal areas troubled district of Kuta Utara indicated seawater intrusion, especially in the area of Petitenget and Batubelig, Kerobokan Kelod Village area of 78.44 Ha. Prediction of sea water intrusion in 2022 was highest in the area of tourism accommodation caused by ground water extraction enough much, kind of gray-brown soil regosol has a rough texture and high permeability characteristics so it is easy to pass groundwater.

Complexes (Ecogroups) of the Invertebrates, Phytomass and Dynamics of Microbiological Population and Their Importance at Grey-brown Soils Diagnostics in Azerbaijan

The objective of this study was to examine the distribution of microorganism, invertebrates, phytomass in grey-brown (chestnut) soils of Garamaryam plateau. Comparative analysis of quantity of microorganisms, soil mezophauna and phytotesting in a phytocenoses and agrocenoses gave us important biodiagnostical results. The complexes (ecogroups) of the invertebrates in the natural and cultivated (cereals, clover) cenozes are comporatively studied with the purpose of their use as biodiagnostical test from grey-brown (chestnut) soils. The results show the quantity of invertebrates, herbs, microorganisms in a grey-brown soils of Garamaryam plateau.

The influence of grape plantations on morphogenetic diagnostic indicators of arid subtropical soils

Abstract Results of the study showed that cultivation of the grey-brown (chestnut) and mountain brown soils under the grape plantation changes their morphogenetic and morphological characteristics in arid subtropical climatic condition. Performed cultivation caused migration of humus into the deeper soil layers. The denser horizon formed under a soft layer. This results in a change of the soil chemical structure and water-physical properties. These changes manifested themselves under irrigative condition.

Magnesium nutrition of apple trees I. Preliminary studies

Symptoms of Mg deficiency on apple trees in the Warsaw district, Central Poland are described and illustrated. Results of soil and leaf analyses of deficient and healthy trees and factors affecting Mg deficiency in apples are discussed. Mg deficiency was found mainly in young trees grown on light, sandy or sandy loamy grey-brown podsolic soils; an old trees it was very rare, because of deep root penetration and utilization of Mg from illuvial horizons rich in Mg. Severe Mg deficiency symptoms appeared on old trees, vigorously growing after topworking with Bancroft scions. Low soil and leaf of Mg content a high available potassium to magnesium ratio in the soil and high ratio in the leaves are suggested to be important factors promoting Mg deficiency symptoms. A three years' experiment run on old Bancroft apple trees showed that 400 kg of MgO applied in epsomite to the soil were as effective as 4 sprays of 2% epsomite. Soil or foliar Mg fertilization did not have any significant effect on tree growth, yields, fruit drop and fruit quality.

Evaluation of the Kur-Araz Lowland Soils of Azerbaijan by Quality

Some special features of the soils depending on natural-historical reality and agricultural production require evaluation of soil quality in a comparative form. From this point study of the contemporary state of the soil fertility of the Kur-Araz lowland of Azerbaijan is one of the problems assuming an important urgency for its evaluation, and hence was objective of this study. The fertility state of 15 main soil types and subtypes of the zone was defined and evaluated by their quality. Grey-brown fertile soils were evaluated with high score 100 and grey or greybrown soils with more salinity and alkalinity areas defined as a soil with low fertility ( 50). In the latter the reclamation methods should be considered for increasing soil quality and production level.

Vegetation of the petropolluted gray-brown soils of Absheron and clarification perspectives of these territories

Vegetation of the petropolluted gray-brown soils of Absheron and clarification perspectives of these territories

Irrigation erosion of irrigated soils in the foothills of southern Kazakhstan

This paper presented the results from the study of irrigation erosion of irrigated lands in southern Kazakhstan. The main purpose of the work is the conservation of the fertility of irrigated soils, and then the soils of the upper, middle and lower sections of the slopes at the experimental site were studied. Based on field investigations, authors studied the water resistance of aggregates of gray-brown soils and light gray soils before and after irrigation and qualitative indicators of changes in physical and chemical properties of structured soils in irrigation were determined by conventional methods of soil research. The results indicated that the changes in the physical properties of soils by using polymeric compounds created a fundamentally new opportunity to control water erosion of soils.

Biodiversity and ecological classification of cryptogamic soil crusts in the vicinity of Petunia Bay, Svalbard

The objective of this study was to describe various types of Arctic soil crust that were collected in the vicinity of Petunia Bay, Svalbard in the 2012 summer season. The photosynthetically active area of different soil crust samples was estimated by a chlorophyll fluorescence imaging camera. Biodiversity of cyanobacteria and microalgae from the collected soil crusts was analyzed using a stereomicroscopy and light microscopy. In most cases, cryptogamic crusts were dominated by cyanobacteria such as Gloeocapsa sp., Nostoc sp., Microcoleus sp., Scytonema sp., and Chroococcus sp. The dominant green microalgae were Coccomyxa sp., Hormotila sp., and Trebouxia sp. which commonly occurred in a lichenised soil crust. Soil crusts that were located in conditions with high water content were dominated by Nostoc sp. Cryptogamic soil crusts from the studied area can be divided into three different types and classified: (1) black-brown soil crusts (with low diversity of cyanobacteria and microalgae), (2) brown soil crusts (with high diversity of cyanobacteria and microalgae) and (3) grey-brown soil crusts (with low diversity of cyanobacteria and algae). The occurrence of similar soil crust types were compared at different altitudes. Altitude does not affect the biodiversity of cyanobacteria and microalgae. However, cyanobacteria and microalgae abundance increases with altitude.

Effect of different potassium soil levels and forms of potassium fertilizers on micro-elemetal nutrion status of apple trees in early fruition period

The experiment was established in the spring of 1999 on grey brown podsolic soil formed from boulder clay. Apple trees of cv. Golden Delicious were planted on rootstock at 3.5×1.2 m (2381 trees⋅ha -1 ). The first factor in the experiment consisted of the levels of potassium in the arable soil layer: 120, 160 and 200 mg K⋅kg -1 of soil d.m., on the basis of annual chemical analyses and determined by universal method. The second factor comprised three forms of potassium fertilizers: potassium chloride (KCl-60%), potassium sulphate (K 2 SO 4 ) and potassium nitrate (KNO 3 ). Each year the analyses of macro- and microelements in the soil and leaves were made. The increase in available potassium levels from 120 to 200 mg K⋅kg -1 of soil d.m did not have influence on the content of available forms of iron, manganese, zinc, copper and boron in the herbicide fallow strips in the tree rows or in the arable (0-20 cm) and subarable (20-40 cm)soil layers. Application of potassium sulphate fertilizer caused a significant increase in the content of zinc in herbicide strips in both soil layers compared with potassium chloride and potassium nitrate. Different potassium fertilizer forms did not cause any significant changes in amounts of available forms of iron, manganese, copper and boron.

菜豆根瘤菌对土壤钾的活化作用

以土壤为钾源,通过液体培养试验研究了8株菜豆根瘤菌对土壤钾的活化作用。结果表明,菜豆根瘤菌能释放大量的氢离子,使液体培养基的pH值大幅度降低,氢离子的浓度至少提高22倍以上。根瘤菌分泌有机酸的种类与数量因菌株不同而异,这些有机酸包括甲酸、乙酸、草酸、丁二酸、柠檬酸、苹果酸和乳酸等,其中全部菌株均能分泌草酸和苹果酸,大部分菌株能分泌乙酸。在接种根瘤菌的液体培养基中,可溶性钾含量显著高于不接种的液体培养基,土壤矿物结构钾则显著降低。由于土壤是培养基钾的唯一来源,故根瘤菌可促进土壤无效钾的溶解。相关分析表明,土壤矿物结构钾与有机酸分泌总量呈极显著负相关(<em>r</em>=-0.878^{* *},<em>n</em>=9),与培养液pH值呈极显著正相关(<em>r</em>=0.863^{* *},<em>n</em>=9),说明根瘤菌分泌的有机酸和氢离子可能溶解土壤无效钾。考虑到根瘤菌草酸分泌量大,络合钙、镁、铁、铝的能力强,且与有机酸分泌总量呈极显著正相关(<em>r</em>=0. 870^{* *},<em>n</em>=9),推测草酸分泌在活化土壤无效钾的过程中起重要作用。此外,根瘤菌分泌的有机酸电离产生的氢离子仅占培养液氢离子的4.15%-27.56%,推测根瘤菌直接分泌的氢离子可能是造成培养液pH值降低的主要原因之一。;Potassium (K) is one of the most important essential elements for plant growth and function. However, both the concentration and the availability of K are very low in most soils. The chemical K supplemented through fertilization is rapidly adsorbed by soil minerals resulting in a 20%-35% of K use efficiency. Studies have found that <em>rhizobia</em>, which have the capacity not only to fix nitrogen from the atmosphere to contribute plant nitrogen nutrition, but also to mobilize soil K for plant use. As a result, the improvement of plant K use efficiency through some specific <em>rhizobia</em> to mobilize soil K has attracted much attention around the whole world. However, less information is available to illustrate the mechanisms how<em> rhizobia</em> could directly mobilize K from the soil. Eight strains of <em>rhizobium</em> sp., which isolated from a gray brown purple soil in Chongqing, southern China and coded as R 01, R 02, R 03, R 04, R 05, R 06, R 07 and R 08, respectively, were grown a liquid medium to study their capacity to mobilize soil K. The medium contained 1L H₂O, 10 g mannitol, 1.0 g yeast powder, 0.5 g NaH₂PO₄, 0.2 g MgSO₄·7H₂O, 0.1 g NaCl, 0.1 g CaCl₂·6H₂O and 4.0 mL microelement solution (each 1 L contained 5.0 g H₃BO₃ and 5.0 g Na₂MoO₄ dH₂O). Compared to the non-<em>rhizobium</em> control, concentrations of proton in the liquid media under all eight <em>rhizobium </em>treatments were increased by 22 times at least leading a significant pH decrease after 7 days of incubation. All <em>rhizobium</em> strains exuded oxalic acid and malic acid and most of them exuded acetic acid, but varied their capacity to exude succinic acid, formic acid, citric acid and lactic acid. Soluble K in the liquid medium was significantly higher whilst mineral structure K was significantly lower in the soil in the <em>rhizobium</em> treatments than in the non-<em>rhizobium</em> control. Mineral structure K in soil negatively correlated with total organic acids (<em>r</em>=-0.878^{* *}, <em>n</em>=9), but positively correlated with pH in the liquid medium (<em>r</em>=0.863^*, <em>n</em>=9). So, <em>rhizobia </em>could mobilize soil K through the exudation of organic acids and protons. Oxalic acid has a strong capacity to complex calcium, magnesium, iron and aluminum and positively correlated with total organic acids (<em>r</em>=0. 870^{* *},<em> n</em>=9), which suggests that oxalic acid exuded by <em>rhizobia </em>might contribute directly in the mobilization of soil K. In addition, protons ionized from organic acids were from 4.15% to 27.56% of the total protons in liquid medium, which showed that <em>rhizobia</em> could exude directly protons and led pH reduction in liquid medium. Our results demonstrated an alternative pathway to enhance plant K nutrition through proton and organic acid exudation could offer a potential effective practice to increase crop productivity by intercropping or growing cereal crops with legumes, in which the latter could not only provide nitrogen, but also to meet the growth requirements of both nitrogen and K for the cereal crops. Nevertheless, more research on the capacity of <em>rhizobia </em>to mobilize soil K and to benefit to its host plants and neighbouring plants are further required.

The flowering pattern of Arnica montana L. and A. chamissonis Less. under field cultivation conditions with successive flower head collection

The research on the flowering of &lt;i&gt;Arnica montana&lt;/i&gt; L. and &lt;i&gt;A. chamissonis&lt;/i&gt; Less. was carried out in the years 2005-2006 on two- and three-year plantations on grey-brown podsolic soil with the granulometric composition of heavy clay sand. The aim of the work was to determine the pattern and length of flowering of two- and three-year-old plants under field cultivation conditions with successive flower head collection. The flowering of &lt;i&gt;Arnica montana&lt;/i&gt; in both years of study lasted 26 days (from the 28&lt;sup&gt;th&lt;/sup&gt; of May to the 22&lt;sup&gt;nd&lt;/sup&gt; of June). In this period, eight collections of flower heads were made. When analyzing the number of inflorescences gathered during particular collections, it was concluded that at the initial stage of flowering it was not great, but it successively increased with the passage of time up to the seventh collection. The pattern of flowering of the two- and three-year-old &lt;i&gt;Arnica montana&lt;/i&gt; plants was similar. The inflorescences of &lt;i&gt;Arnica chamissonis&lt;/i&gt; were collected six times, and the most abundant flowering was found in the middle period of this stage, which lasted 20 days.

Effect of long-term urban wastewater irrigation on heavy metal contamination of soils under conditions of Egypt

It is established that, with wastewater irrigation of corn on alluvial and gray-brown desert soils, the total content of heavy metals and their mobile compounds increases. However, the content of Zn, Cu, Ni, and Co didn’t exceed the maximum allowable concentration. But Cd and Pb exceeded the maximum allowable concentration during long-term wastewater irrigation of alluvial soils. Irrigation with ground, river, and waste waters for 3 years didn’t lead to considerable heavy metal contamination of soils.

Effects of rock fragments on infiltration and evaporation in hilly purple soils of Sichuan Basin, China

This paper presents the results of laboratory experiments showing the effects of rock fragments contained in three different purple soils of the Sichuan basin of southwest China. The experiments investigated how these rock fragments alter the soil’s physical, chemical, and agronomical characteristics such as infiltration and evaporation. We found that the infiltration rate, whether horizontal or vertical, in the three soils has the following order: gray brown purple soil < reddish brown purple soil < brown purple soil. With increasing rock fragment contents the accumulated infiltration decreases, while the total time decreases first and then increases. The minimum occurs at approximately 10–20% of fragment content by weight. The infiltration rate also changes with the distance. In the 0–5 cm range, the initial infiltration rate increases with increasing rock fragment contents, while in the 5–10 cm range, the slope of infiltration curve increases with increasing rock fragment contents. With increasing distance, the slope gradually decreases and finally reaches a stable value. The presence of rock fragments reduces soil water content, the minimal value appearing when the rock fragments were on top of the soil column (soil + rock sample), decreasing with increasing rock fragments for other samples mixed with fragments. Under the constant 40°C temperature, the accumulated evaporation and evaporation rate are minimal for soils covered by rock fragments, and the accumulated evaporation decreases with increasing rock fragment for other soil samples. However, the evaporation rate increases with increasing rock fragments in the first 4 days and decreases thereafter.

Effect of crude oil pollution on organic carbon and humus content in grey-brown soils in Mangyshlak, Pre-Caspian Sea Region

The organic carbon and humus content in oil polluted brown and grey-brown soils in Mangyshlak, Pre-Caspian Sea Region, was analyzed from 2000 to 2008. The results indicated that bitumen substances from crude oil pollution deteriorated the soil property, however, the organic carbon content increased significantly. The products of oil pollution changed the composition of car- bonaceous substances which formed soil humus, and changed the ratios of the humus components. Residual insoluble carbon increased with the rise of oil organic carbon. The mobility of humus components was significantly increased because of the high oxidation-reduction process in the topsoil, and the humus content and microorganism activity increased. The organic carbon content increased significantly, while it decreased with the distance away from the oil well. The rearrangement of physical, physical-chemical and chemical properties of the polluted soils was significant.

Soil Aggregation and Its Relationship with Organic Carbon of Purple Soils in the Sichuan Basin, China

The interaction of soil aggregate dynamics with soil organic carbon is complex with varied spatiotemporal processes in macro-and micro-aggregates. This paper is to determine the aggregation of soil aggregates in purple soils (Regosols in FAO Taxonomy or Entisols in USDA Taxonomy) for four types of land use, cropland [corn (Zea mays L.)], orchard (citrus), forestland (bamboo or cypress), and barren land (wild grass), and to explore their relationship with soil organic carbon in the Sichuan basin of southwestern China. Procedures and methods, including manual dry sieving procedure, Yoder's wet sieving procedure, pyrophosphates solution method, and Kachisky method, are used to acquire dry, wet, and chemically stable aggregates, and microaggregates. Light and heavy fractions of soil organic carbon were separated using 2.0 g mL-1 HgI2-KI mixed solution. The loosely, stably, and tightly combined organic carbon in heavy fraction were separated by extraction with 0.1 M NaOH and 0.1 M NaOH-0.1M Na4P2O7 mixed solution (pH 13). The results show that the contents of dry and wet macroaggregates > 0.25 mm in diameter were 974.1 and 900.0 g kg-1 highest in red brown purple soils under forestland, while 889.6 and 350.6 g kg-1 lowest in dark purple soil and lowest in grey brown purple soils under cropland, respectively. The chemical stability of macroaggregates was lowest in grey brown purple soil with 8.47% under cropland, and highest in red brown purple soil with 69.34% under barren land. The content of microaggregates in dark purple soils was 587 g kg-1 higher than brown purple soils, while 655 g kg-1 in red brown purple soils was similar to grey brown purple soils (651 g kg-1). Cropland conditions, only 38.4% of organic carbon was of the combined form, and 61.6% of that existed in light fraction. Forestland conditions, 90.7% of organic carbon in red brown purple soil was complexed with minerals as a form of humic substances. The contents and stability of wet aggregates > 0.25 mm, contents and stability of chemically stable aggregates > 0.25 mm, contents of microaggregates > 0.01 mm, contents of aggregated primary particle (d < 0.01 mm) and degree of primary particles (d < 0.01 mm) aggregation were closely related to the concentrations of total soil organic carbon, and loosely and tightly combined organic carbon in heavy fraction. Soil microaggregation could be associated with organic carbon concentration and its combined forms in heavy fraction. There was a direct relationship between microaggregation and macroaggregation of soil primary particles, because the contents of wet aggregates > 0.25 mm and its water stability of aggregates were highly correlated with the contents of aggregated primary particle (d < 0.01 mm) and the degree of primary particles (d < 0.01 mm) aggregation.

Ocena rozwoju osobniczego (ontogenezy) chwastów w łanie lnu włóknistego

The study was conducted according to observations of ontogenesis of weeds found in the field of fibrous flax conducted in 2005–2006. The field experiments were conducted at INF Experimental Farms Stary Sielec and P tkowo (wielkopolskie district). Experiments were set on two types of soil: grey brown podsolic and black earth. The phenological development of flax and weeds was evaluated according to BBCH scale. &#x0D; On black earth soil (good wheat agricultural soil complex) the full ontogenesis was recorded for the following taxa: Geranium pusillum L., Viola arvensis Murr., Stellaria media Vill., Chenopodium album L., Matricaria maritima L. ssp. inodora (L.) Dostal, Galium aparine L., Polygonum lapathifolium L., Capsella bursa-pastoris (L.) Med., Euphorbia cyparissias L., Galinsoga parviflora Cav. and Elymus repens (L.) Goud. On grey brown podsolic soil (good rye agricultural soil complex) few weed species reached flowering or green maturity stage (BBCH 60–73): Chenopodium album L., Polygonum aviculare L., Polygonum persicaria L. and Anthemis arvensis L. Most weeds senesced before completion of full development cycle on the lighter soil. Environmental conditions had stronger effect on development of weeds than on ontogenesis of fibrous flax.

Geological and pedological aspects of an Early-Paleolithic site: Revadim, Central Coastal Plain, Israel

An Early Paleolithic site was recently discovered within a sequence of paleosols in the Revadim Quarry, central coastal plain of Israel. The section is composed of three superimposed soils in a continuous sequence, but separated by two unconformity surfaces. The uppermost paleosol is a modern Dark Brown Grumusol (Vertisol), the middle is a Quartzic Gray Brown Soil (Haploxeralf), and the lower is a Red Hamra (Rhodoxeralf). Normal magnetic polarity was detected in the two lower soils, indicating that they are younger than the Brunhes–Matuyama boundary (<780 ka). A human occupation bed, enriched in secondary carbonate nodules, forms the lower part of the Quartzic Gray Brown Soil and overlies the Red Hamra. The living floor is located on top of the unconformity surface, separating the Red Hamra from the overlying Quartzic Gray Brown Soil. Middle to Late Acheulian handaxes, choppers, cores, and flake tools, including tools made by the Levallois technique, and man-laid flint pebbles were excavated in the human occupation bed. In addition, two elephant tusks, an elephant pelvis, an elephant tooth (Palaeoloxodon antiquus), tusk splinters, and bones of equid, suid, cervid, bovid, felid, and rodents were also collected. Based on well-documented nearby boreholes and on regional correlation, it appears that the underlying dune sands, the parent materials from which the Red Hamra developed, were deposited probably during a phase of high-stand sea level of Isotope Stage 9. The Red Hamra developed simultaneously with the human occupation of the site, probably during a phase of low-stand sea-level of Isotope Stage 8, before some 300–245 ka. The overlying dune sands, the parent materials from which the Quartzic Gray Brown Soil developed, were deposited probably during a phase of high-stand sea level of Isotope Stage 7. The climate prevailing in the area during Stage 8, as well as during the human habitation, was moist, with a dense vegetation cover of grassland and probably scattered trees. A small lake of trapped fresh water at a junction of two small tributaries of the Soreq River drainage system near the area occupied was available to hominids and animals. © 1999 John Wiley & Sons, Inc.

Long-term changes in pH of forest soils in southern Sweden

Changes in pH in 22 forest soils ( Fagus, Carpinus, Quercus, Picea) and one Calluna health from southern Sweden were examined in 1984 by repeating studies originally made in 1949–1970. The topsoil had become more acid in 1984 with pH decreases in the old profiles of more than 1·0 in less acid soils and of 0·5 in acid soils. Younger profiles also showed pH decreases, although of a smaller magnitude. Soil pH had, on the whole, declined, and acid deposition is probably a main contributor. Acidification has also occurred in deeper horizons, most markedly in 30–35-year-old horizons. Podsols had largest pH decreases in deeper horizons, and grey-brown soils in the upper profile.

Field Performance in Soybean with Seeds of Differing Size and Density1

A 2‐yr field experiment was conducted to determine if separation of soybean [Glycine max (L.) Merr.] seeds by size or density might be effective in improving seedling emergence, speed of emergence, or yield. Eighteen soybean seedlots were separated into four size classes using round—hole screens, and into two density classes by floating low density seeds on sucrose solutions. These seeds were planted in a Typic Hapludalf—grey brown podsolic soil type. Seeds of largest size and seeds of lowest density had the lowest percent emergence and speed of emergence, provided these seeds came from seedlots of intermediate vigor. Seed size and density effects were greater when seeds were subjected to greater field stresses of low temperature and wet or crusted soils. The stand differences due to seed size and density persisted until harvest maturity. If compared to the unseparated control, only the smallest seed size was superior in emergence and speed of emergence, and high density seed did not show any advantage. Seed size had no effect on yield in early or late plantings, but high density seeds outyielded low density seeds in the late plantings. High density seeds did not outyield the unseparated seeds. In general, the effects of seed size and seed density on percent emergence, speed of emergence, and yield indicate that the potential for large scale vigor improvement in soybean seedlots through processing or conditioning is limited.

Long term effects of rice growing on some chemical properties of two soils of northern Australia

Solodic soils (Natrustalfs) of the Lower Burdekin Valley, Qld, and grey-brown clays (Chromusterts) of the Ord Irrigation Area, W.A., of varying rice cropping histories, were analysed before and after a laboratory flooding experiment to determine whether any long-term changes in chemical fertility had occurred. In the solodic group changes in the extractability of iron and manganese in acetate and oxalate reagents indicated that oxides of these elements may be more easily reduced in soils that had grown nine or more rice crops than in soils which had not been used for rice growing. The flooding experiment showed that manganese and iron reduction and the mobilization of phosphorus were more rapid in the solodic soils which had been used for rice than those which had not. Iron reduction did not occur in the flooded grey-brown clays, and manganese reduction was apparent only in three soils, but was most rapid in those which had grown 15 rice crops. Extractable phosphorus levels decreased during flooding of the grey-brown clays, but this was not related to the cropping history. There were small increases in sodicity of the subsoil (40-50 cm) of the solodic soils which had been used for rice growing. It was concluded that for the solodic soils rice growing leads to soils more favourable for further rice growing but less favourable for non-flooded crops, whereas this effect was not shown for the grey-brown clay soils.