Particle-size effects on soil temperature, evaporation, water use efficiency and watermelon yield in fields mulched with gravel and sand in semi-arid Loess Plateau of northwest China

Gravel and sand mulch is an effective practice in conserving soil and moisture. However, the proportion of different particle size in this kind of mulch layer is an important factor to be considered in order to obtain optimal results from this practice. From 2005 to 2007, a series of experiments including one with watermelon were conducted in the semi-arid Loess Plateau of northwest China to determine the influence of particle size and its proportion in mulch layer on soil temperature, evapotranspiration, water use efficiency (WUE) and watermelon (Citrullus lanatus L.) yield. The treatments in no-watermelon experiments included particle sizes classified as <0.3, 0.3-1, 1-2, 2-4, 4-6, 6-8 and 8-10 cm mesh size or various rates of 2-6 cm pebble accounting for 0, 10, 20, 30, 40, 50, 60 and 70% with 30% 1-2 cm gravel-sand in mulch layer (as well as correspondingly decreasing sand proportions). The watermelon experiment included three particle sizes, 0.3-1, 1-2 and 2-6 cm. Soil temperature at 8:00 h was highest for the 1-2 cm treatment, and the daily average temperature at 14:00 h was highest for the 0.3-1 cm treatment. Soil temperature decreased with particle size increasing due to porosity enlarging. The relationship between soil temperature and particle size followed a quadratic or cubic curve. Soil temperature was increased by gravel-sand mulch plus plastic film. The increment of soil temperature was larger especially for 1-4 cm particle size. In the gravel-sand mulch layer having different size particles, the greater percentage being of 2-6 cm pebbles, increases porosity, and lowers soil temperature, and causes more evaporation. The results of the watermelon experiment showed that soil moisture before seeding would not affect the yield during the years of using gravel mulch. Watermelon yield and WUE were higher for 1-2 and 0.3-1 cm treatments than 2-6 cm treatments in later experiments during 2006 and 2007. In conclusion, 2-6 cm large size particles would not account for much in gravel-sand mulching layer. It would be better if the percentage of 2-6 cm particles was less than 30%.     

Effects of rainfall harvesting and mulching technologies on water use efficiency and crop yield in the semi-arid Loess Plateau, China

In semi-arid areas, crop growth is greatly limited by water. Amount of available water in soil can be increased by surface mulching and other soil management practices. Field experiments were conducted in 2005 and 2006 at Gaolan, Gansu, China, to determine the influence of ridge and furrow rainfall harvesting system (RFRHS), surface mulching and supplementary irrigation (SI) in various combinations on rainwater harvesting, amount of moisture in soil, water use efficiency (WUE), biomass yield of sweet sorghum (Sorghum bicolour L.) and seed yield of maize (Zea mays L.). In conventional fields without RFRHS, gravel-sand mulching produced higher biomass yield than plastic-mulching or straw-mulching. In plastic-mulched fields, an increasing amount of supplemental irrigation was needed to improve crop yield. There was no effect of RFRHS without plastic-covered ridge on rainwater harvesting when natural precipitation was less than 5 mm per event. This was due to little runoff of rainwater from frequent low precipitation showers, and most of the harvested rainwater gathered at the soil surface is lost to evaporation. In the RFRHS, crop yield and WUE were higher with plastic-covered ridges than bare ridges, and also higher with gravel-sand-mulched furrows than bare furrows in most cases, or straw-mulched furrows in some cases. This was most likely due to decreased evaporation with plastic or gravel-sand mulch. In the RFRHS with plastic-covered ridges and gravel-sand-mulched furrows, application of 30 mm supplemental irrigation produced the highest yield and WUE for sweet sorghum and maize in most cases. In conclusion, the findings suggested the integrated use of RFRHS, mulching and supplementary irrigation to improve rainwater availability for high sustainable crop yield. However, the high additional costs of supplemental irrigation and construction of RFRHS for rainwater harvesting need to be considered before using these practices on a commercial scale.     

Control and prevention of contact infection of brown rot disease with fosetyl-aluminium,and residue levels in post-harvest-treated citrus fruits

The effect of fosetyl-aluminium on the control and spread of brown rot disease Phytophthora citrophthora in post-harvest citrus fruit was studied in laboratory and semi-commercial experiments. Aqueous solutions of fosetyl-aluminium at 5 to 10 g a.i. litre^?1 controlled the fungus even when applied 3 days after inoculation at 17°C. No mycelia developed on the peel surface of treated fruit. The fungicide exerted a good prophylactic effect on healthy fruit, protecting them during storage from contact inoculation. Fosetyl-aluminium also showed a fungitoxic effect in vitro and in vivo on other fungi which developed in harvested citrus fruits. Residue levels of phosphoric acid in the treated fruit were higher when the fungicide was incorporated in the wax coating the fruit than when applied in aqueous solution, and levels were lower in the pulp than in the peel. It is concluded that fosetyl-aluminium is a suitable commercial post-harvest treatment for control of brown rot in citrus fruits.     

Dacryocystomaxillorhinostomy for chronic dacryocystitis in a dog

A 10-year-old female spayed Vizsla had intermittent mucoid ocular discharge from the right eye for 7 years. History, clinical findings, imaging studies, and culture and histopathology results confirmed chronic dacryocystitis with granuloma. A dacryocystomaxillorhinostomy was performed to preserve the functional portions of the nasolacrimal system remaining in this patient, as well as to promote healing of the lacrimal sac granuloma and secondary infection. Complete resolution of the clinical abnormalities was achieved, and the dog remains healthy 3 years postoperatively.     

Lupane-type saponins from leaves of Acanthopanax sessiliflorus and their inhibitory activity on pancreatic lipase

Three known saponins, chiisanoside, 11-deoxyisochiisanoside, and isochiisanoside, and one novel saponin, 3,4-seco-4(23),20(29)-lupadiene-3,28-dioic acid 28-O-alpha-l-rhamnopyranosyl (1-->4)-beta-d-glucopyranosyl (1-->6)-beta-d-glucopyranoside, referred to as sessiloside, were isolated from a hot water extract of Acanthopanax sessiliflorus leaves. All of these saponins were lupane-type triterpene triglycosides, and their concentrations were 4.1, 1.0, 0.5, and 0.4% (w/w) of the total extract, respectively. Sessiloside and chiisanoside inhibited pancreatic lipase activity in vitro, and addition of the saponin-rich fraction to a high-fat diet suppressed the body weight gain of mice. The possibility of application of the lupane-type saponins from A. sessiliflorus leaves to the treatment of obesity is discussed.     

Effect of tillage and furrow irrigation timing on efficiency of preplant irrigation

Summary A field study to determine the efficiency of preplant irrigating with furrow irrigation and the effects of tillage and fall or spring application of preplant irrigation on this efficiency was conducted during 1983, 1984, and 1985 at the Texas Agricultural Experiment Station, North Plains Research Field at Etter, Texas on a Sherm, silty clay loam soil. Sorghum residue from the previous crop was shredded, gravimetric soil samples were taken, and five tillage treatments were imposed in the fall. The tillage treatments consisted of various combinations of disking, chiselling, moldboard plowing, and disk bedding. A preplant irrigation was applied in the fall to half of each tillage plot and in the spring to the other half of each plot. Soil samples were taken from each plot one month after the spring preplant irrigation. Sorghum (Sorghum bicolor L. cv. NC 178) was planted and irrigated similarly on all plots during the growing season. On the average, 237 mm of water were required to irrigate the tillage treatments during fall preplant irrigation and 466 mm were required during spring preplant irrigation. The additional water requirement in the spring was associated with increased water uptake by non-wheel-track furrows. Treatments with chiselling required larger water application during spring preplant irrigation. All treatments had similar soil water contents at planting time. Neither timing of preplant irrigation nor type of tillage had any effect on sorghum grain yield. Therefore, fall preplant irrigation was considerably more efficient than spring preplant irrigation. Averaged over the three years do study and five tillage treatments storage efficiency was 26% for fall application and 17% for springtime.Contribution of the Texas Agricultural Experiment Station, Paper No. 21724     

Prediction of phytotoxicity and uptake of metals by models in proposed USEPA 40 CFR part 503 sludge regulations: Comparison with field data for corn and wheat

The United States Environmental Protection Agency (USEPA) has recently (February 6, 1989) proposed the 40 CFR Part 503 regulations which govern sludge use and disposal. The numerical limits on cumulative soil metal loading rates in these regulations were generated through risk assessment analysis based on modeling metal flux through several terrestrial pathways. Field data from a 6300 ha dedicated land application site operated by the Metropolitan Water Reclamation District of Greater Chicago (District) since 1972 indicate that these pathway models do a poor job of predicting bioaccumulation of Cd, Cu, and Zn in corn leaf and grain and wheat grain tissue. The USEPA pathway model does not take soil pH into account and predicts that plant tissue concentration will be linearly related to metal loading rates in soil. District field data indicate that crop tissue metal concentrations are dependent on soil pH and increase at low metal loadings but then become independent of total metal loading rate. No phytotoxicity was observed in corn or wheat despite soil loading rates for Cr, Cu, Ni, and Zn that were 13, 28, 3, and 16 times higher than their respective phytotoxic thresholds predicted by the USEPA pathway model.