Liming Effects on Nitrate Adsorption in Soils With Variable Charge Clays and Implications for Ground Water Contamination

The present research sought to determine the extent and distribution of nitrate accumulation in the subsoils of central Oahu, and to measure the consequences of surface applied amendments on nitrate mobility. Deep bore holes collected from pineapple fields in central Oahu were analyzed for nitrate and nitrate adsorption, and a lime incubation experiment and column study were conducted. Three and one half to 11 T/ha of nitrate-N have been measured in subsoils and the deep. saprolitic vadose zones of pineapple fields located in central Oahu, Hawai’i. Nitrate adsorption isotherms confirmed the high nitrate retention capacity of the materials in the subsoil and saprolite. Since large areas of former sugarcane land are being converted to diversified crops requiring amendments to reduce acidity, a lime incubation study was conducted on soils from former sugarcane land to investigate the effect of lime on nitrate adsorption. When lime was added to acid subsoils, nitrate retention was decreased by up to one half of the native adsorption capacity. A leaching experiment found that surface applied lime and gypsum increased nitrate mobility through soil columns 50 cm in length. The data indicate that large quantities of nitrate have accumulated in the subsoil overlying the Pearl Harbor aquifer. Mobility of nitrate through the subsoil is retarded, but a laboratory column study shows that nitrate mobility can be increased by adding lime and gypsum to the surface soil. Field studies need to be conducted to evaluate the potential for ground water contamination as a result of surface applied amendments

Acidification of Volcanic Ash Soils from Maui and Hawai‘i Island for Blueberry and Tea Production

This publication provides background on soil acidity in relation to plant growth, presents approaches to acidifying soils, and provides guidelines for the acidification of some volcanic soils on Maui and Hawai‘i island that are potential sites for tea and blueberry production

Edaphic controls of soil organic carbon in tropical agricultural landscapes

Predicting soil organic carbon (SOC) is problematic in tropical soils because mechanisms of SOC (de)stabilization are not resolved. We aimed to identify such storage mechanisms in a tropical soil landscape constrained by 100 years of similar soil inputs and agricultural disturbance under the production of sugarcane, a C-4 grass and bioenergy feedstock. We measured soil physicochemical parameters, SOC concentration, and SOC dynamics by soil horizon to one meter to identify soil parameters that can predict SOC outcomes. Applying correlative analyses, linear mixed model (LMM) regression, model selection by AICc, and hierarchical clustering we found that slow moving SOC was related to many soil parameters, while the fastest moving SOC was only related to soil surface charge. Our models explained 78-79%, 51-57%, 7-8% of variance in SOC concentration, slow pool decay, and fast pool decay, respectively. Top SOC predictors were roots, the ratio of organo-complexed iron (Fe) to aluminum (Al), water stable aggregates (WSagg), and cation exchange capacity (CEC). Using hierarchical clustering we also assessed SOC predictors across gradients of depth and rainfall with strong reductions in Roots, SOC, and slow pool decay associated with increasing depth, while increased rainfall was associated with increased Clay and WSagg and reduced CEC in surface soils. Increased negative surface charge, water stable aggregation, organo-Fe complexation, and root inputs were key SOC protection mechanisms despite high soil disturbance. Further development of these relationships is expected to improve understanding of SOC storage mechanisms and outcomes in similar tropical agricultural soils globally

Primary PEComa of the bladder treated with primary excision and adjuvant interferon-alpha immunotherapy: a case report

BACKGROUND: Perivascular epithelioid cell tumors (PEComas) are rare mesenchymal neoplasms of uncertain malignant potential, which have in common the co-expression of muscle and melanocytic immunohistochemical markers. CASE PRESENTATION: A 48-year-old man presented with dysuria, passage of urinary sediment and lower abdominal discomfort. A three centimeter mass was identified by cystoscopy in the posterior midline of the bladder. Computerized tomography suggested an enterovesical fistula. The patient underwent laparotomy, partial cystectomy and partial small bowel resection. Pathological examination revealed PEComa of the bladder. The patient underwent adjuvant interferon-α immunotherapy. Subsequent follow-up procedures, including cystoscopy and imaging, have not revealed evidence of recurrence. The patient is clinically free of disease 48 months after surgery. CONCLUSION: This case represents the second documented PEComa of bladder and demonstrates that adjuvant therapies, including anti-angiogenic and immunotherapy, may be considered for patients with locally advanced or metastatic genitourinary PEComa

The Potential Benefits and Limitations of Corn Cob and Sewage Sludge Biochars in an Infertile Oxisol

The thermal conversion of sewage sludge to biochar offers a promising alternative use for a hazardous waste material with potential benefits to agricultural productivity and soil quality. Three short-term greenhouse experiments were conducted to evaluate the effect of corn cob (CC) and sewage sludge (SS) biochars, with their anaerobically treated counterparts, on soil properties and plant growth in an infertile Oxisol. The anaerobically treated SS biochar showed the greatest concentration of bioavailable essential nutrients, but treatment only resulted in increased yields for the SS biochar in the first crop in the absence of added fertilizer. Both CC and SS biochars in combination with fertilizer doubled plant growth compared to the control in the first crop cycle, produced no significant effect in the second cycle, and more than tripled plant growth for the SS biochars in the third cycle. High ash content with high nutrient contributions (especially P) and a persistent liming effect explain the benefits of the SS biochars to plant growth. The SS biochar showed promise in mitigating the negative effects of soil Mn toxicity. Sewage sludge biochars reduced Cd bioavailability and had no significant effect on the bioavailability of other potentially toxic metals compared to the control

Nitrogen Mineralization Potential in Important Agricultural Soils of Hawai'i

Soil microorganisms convert nitrogen in soil organic matter into inorganic forms that plants can take up; the process is called N mineralization. The N cycle and factors affecting mineralization are reviewed. Mineralization potential of five Hawaiian soils is described

Correcting soil nutrient deficiencies with organic materials in the atoll soils of the Marshall Islands

The coralline soils of atolls suffer from multiple nutrient deficiencies that severely limit crop growth. This study was conducted to assess the nutrient status of the soils of the inhabited atolls within the Marshall Islands (MI), and to determine what local materials could be used to correct deficiencies limiting crop growth. Surface and subsoils from 25 atolls were collected and analyzed for their chemical properties, and soil test results were evaluated with a missing element pot study. Soil tests revealed that the MI soils were severely deficient in K (0.12 cmol c kg -1 ) and marginally deficient in Cu (0.13 ug g -1 ). The missing element study showed that the soil was deficient in K, S, N, P, and Cu. An incubation experiment and a series of greenhouse experiments were conducted to evaluate the ability of locally available organic materials to mineralize N and supply adequate nutrients to crops. Vigna marina and fish meal showed the highest N mineralization capacity, and the Gompertz equation provided the best fit. Chinese cabbage plants grew as well in soils amended with chicken manure, Vigna marina , and copra cake as they did in soil treated with chemical fertilizers. Plants grown in soil amended with fish meal did not grow as well due to inadequate K supply. Nitrogen recovery was highest in V. marina treatment at 92% followed by the chemical control (83%), chicken manure (34%), fish-meal (18%), and copra cake (9%). Added coconut leaves immobilized N and resulted in very poor cabbage growth. Comparisons between relative growth rate (RGR) and nutrient relative accumulation rate (RAR) showed that nutrients supplied from the V. marina amendment to the cabbage plant matched plant demand. In a rate experiment in the greenhouse, adding 10.1 g kg -1 of V. marina leaves (dry weight) supplied 350 mg N kg -1 to 5 week-old corn plants representing 38% of the total amount of N added in the amendment. Splitting the application quantity improved corn growth at the highest addition rate. Copra cake showed less promise as a suitable organic amendment. Supplementing copra with chemical N and P, and V. marina leaves with and without Cu and B did not improve crop growth compared with copra alone. The soil exhibited low P adsorption capacity, and corn and lettuce growth responded to high Olsen P soil levels. The results of the greenhouse experiments showed that V. marina is a potential organic fertilizer material to correct soil nutrient deficiencies for good crop growth in the Marshall Islands

Biochar Volatile Matter and Feedstock Effects on Soil Nitrogen Mineralization and Soil Fungal Colonization

Biochar has important biogeochemical functions in soil—first as a means to sequester carbon, and second as a soil conditioner to potentially enhance soil quality and fertility. Volatile matter (VM) content is a property of biochar that describes its degree of thermal alteration, which can have a direct influence on carbon and nitrogen dynamics in soil. In this study, we characterized the VM in biochars derived from two locally sourced feedstocks (corncob and kiawe wood) and evaluated the relationship of VM content to nitrogen transformations and culturable fungal biomass. Using 13C nuclear magnetic resonance (NMR) spectroscopy, we found that the VM content of biochar primarily consisted of alkyl (5.1–10.1%), oxygen-substituted alkyl (2.2–6.7%), and phenolic carbon (9.4–11.6%). In a series of laboratory incubations, we demonstrated that corncob biochars with high VM (23%) content provide a source of bioavailable carbon that appeared to support enhanced viable, culturable fungi (up to 8 fold increase) and cause nitrogen immobilization in the short-term. Corncob biochar with bioavailable VM was nitrogen-limited, and the addition of nitrogen fertilizer resulted in a four-fold increase in total hydrolytic enzyme activity and the abundance of culturable fungal colonies. In contrast, kiawe biochar with an equivalent VM content differed substantially in its composition and effect on these same biological parameters. Therefore, the rapid measurement of VM content is too coarse to differentiate chemical composition and to predict the behavior of biochars across feedstocks and production methods

Response of selected soil physical and hydrologic properties to manure amendment rates, levels, andtypes

Manure amendments affect several soil physical and hydrologic properties. The objectives of this study were to evaluate the effect of (i) manure amendment rates (0, 168, 336, and 672 kg total N ha), levels (one-time application, and two-time application), and types (chicken manure [CM], dairy manure [DM], and swine manure [SM]) on bulk density (ρb), total soil porosity (θt), and saturated hydraulic conductivity (Ksat) of a highly weathered tropical soil (Waialua gravely clay variant, isohyperthermic Pachic Haplustolls) and (ii) measuring instruments (tension infiltrometer [TI] and double-ring infiltrometers [DR]) on Ksat. For the two-time application level, all the plots received additional manure to compensate for the amounts decomposed during the first growing season. The field was tilled to the top 15-cm depth before and after manure application during the two growing seasons. Measurements of ρb and θt were conducted on undisturbed soil core samples collected from the top 10 cm of soil from a field cultivated with sweet corn (Zea mays L. subsp. mays) and irrigated with a drip irrigation system for two consecutive growing seasons. Saturated hydraulic conductivity was calculated from steady state infiltration rates measured with TI and DR. Results show that the increased manure amendment rates and levels significantly (P \u3c 0.01) decreased ρb and consequently increased θt. The values of Ksat increased significantly (P \u3c 0.01) with increase in CM and DM amendment rates and levels. For SM treatments, the values of Ksat decreased with increase in manure amendment rates and levels; these results concur with those reported in literature on liquid manures. Saturated hydraulic conductivity calculated from DR data was slightly greater than that from TI data for CM and DM treatments. Opposite results were found for SM treatments. However, a good agreement (R = 0.90) was observed between Ksat values calculated from TI and DR data across treatments. We conclude that the CM and DM amendments increased θt and Ksat and may also temporarily improve soil aggregation; however, SM amendments result in decreased Ksat. Thus, it is not recommended that slurry SM be applied to the soils with low hydraulic conductivity because it could further inhibit water infiltration and increase surface runoff and soil erosion. © 2008 ippincott Williams & Wilkins