甘蔗花生间作下不同氮磷钾配施对花生养分吸收及产量效益的影响

为提高华南区甘蔗间作花生的经济效益,研究不同氮磷钾配施对花生养分吸收及产量效益的影响。田间试验设置氮磷钾肥各4个水平梯度,比较氮磷钾不同配比的施肥对花生养分吸收和产量效益的影响。结果表明：氮磷肥施用量增加促进间作花生对氮磷养分的吸收,而钾肥施用过量会抑制花生对钾养分的吸收。开花下针期到荚果膨大期是间作花生干物质积累、吸收养分的关键时期。间作花生干物质累积量随氮磷钾肥施用量的增加而增加,每形成1000 g的干物质,就需要吸收同化17.7 g N、1.7 g P₂O₅和11.3 g K₂O,吸收比列为10.4∶1∶6.6（N∶P₂O₅∶K₂O）。间作花生生产百千克荚果需吸收氮、磷、钾养分量分别在6.83~7.98 kg N、0.65~0.80 kg P₂O₅、4.10~5.32 kg K₂O之间。综上,华南区种植与甘蔗间作的花生,较优氮磷钾施肥配比为80 kg/hm² N,70 kg/hm² P₂O₅,80~90 kg/hm² K₂O,可提高花生产量和经济效益,以及养分吸收利用率。     

Dyeing and fastness properties of a reactive disperse dye on PET, nylon, silk and N/P fabrics

Dyeing and color fastness properties of a reactive disperse dye containing an acetoxyethylsulphone group on PET, Nylon, silk and N/P fabrics were examined. The reactive disperse dye exhibited almost the same dyeing properties on PET fabric as a conventional disperse dye except the level of dye uptake. The most appropriate pH and dyeing temperature for the dyeing of Nylon fabric were 7 and 100°C respectively. The build-up on Nylon fabric was good and various color fastnesses were good to excellent due to the formation of the covalent bond. Application of the reactive disperse dye on silk fabric at pH 9 and 80°C yielded optimum color strength. The rate of dyeing on Nylon fabric was faster than that on PET fabric when both fabrics were dyed simultaneously in a dye bath, accordingly color strength of the dyed Nylon was higher. The reactive disperse dye can be applied for one-step and one-bath dyeing of N/P mixture fabric with good color fastness.     

Response of plant species composition,biomass production and biomass chemical properties to high N,P and K application rates in Dactylis glomerata‐ and Festuca arundinacea‐dominated grassland

Little is known about the immediate effect of high nitrogen (N), phosphorus (P) and potassium (K) application rates on sown grasslands cut twice per year. We asked how quickly plant species composition, biomass yield, biomass chemical properties and nutrient balance respond to N, P and K application. An experiment using unfertilized control, P, N, NP and NPK treatments was established on seven‐year‐old cut grassland in the Czech Republic in 2007 and monitored over four years. Annual application rates were 300 kg N ha^?1, 80 kg P ha^?1 and 200 kg K ha^?1. The immediate response of plant species composition to N application was recorded and was found to be different to the response over the four years of the study period. Highly productive grasses (Dactylis glomerata, Festuca arundinacea and Phleum pratense) were promoted by N application in 2008 and then retreated together with legumes (Medicago sativa, Trifolium pratense and Trifolium repens) in all N treatments where the expansion of perennial forbs (Urtica dioica and Rumex obtusifolius) and annual weeds (Galinsoga quadriradiata, Impatiens parviflora, Lamium purpureum and Stellaria media) was recorded. At the end of the experiment, Festuca rubra was the dominant grass in the control and P treatment, and species richness was lowest in all treatments with N application. Mean annual dry‐matter yield over all years was 3.5, 3.9, 5.8, 5.6 and 6.8 t ha^?1 in the control, P, N, NP and NPK treatments, respectively. Concentrations of N in the biomass ranged from 20.0 to 28.7 g kg^?1 in the P and N treatments; concentrations of P ranged from 3.2 to 3.7 g kg^?1 in the N and P treatments; and concentrations of K ranged from 24.1 to 34.0 g kg^?1 in the NP and NPK treatments. The N:P, N:K and K:P ratios did not correctly indicate the nutrient limitation of biomass production, which was primarily N‐limited, and K‐limitation was only recorded for high production levels in treatments with N applications. On the basis of the nutrient‐balance approach, the balanced annual application rates were estimated as 140 kg N ha^?1, 30 kg P ha^?1 and 100 kg K ha^?1. We concluded that high N, P and K application rates can very quickly and dramatically change species composition, biomass production and its chemical properties in sown cut grasslands. High N application rates can be detrimental for tall forage grasses and can support the spread of weedy species.     

Responses of herbage P,Ca, K and Mg content and Ca/P and K/(Ca + Mg) ratios to long‐term continuous and discontinued cattle grazing on a rough fescue grassland

Herbage minerals affect performance of grazing cattle. We investigated the response of herbage P, K, Ca and Mg contents and Ca/P and K/(Ca + Mg) ratios to long‐term stocking rate, continuous vs. discontinued grazing practice, and sampling year. Cattle had been stocked at 2·4 and 4·8 animal unit months ha^?1 since 1949. Exclosures were installed in April 1998. Herbage samples were collected near peak herbage mass in 2001, 2003, 2008 and 2012 and analysed for mineral content. Mineral contents were similar between the two stocking rates, but were lower (P < 0·05) under discontinued than continuous stocking, with the exception of similar P contents. The content of P and K in herbage was higher and the content of Ca and Mg was lower (P < 0·05) in years with greater precipitation and lower temperatures. Herbage mineral content, with the exception of P, exceeded minimum recommended levels for cattle. Given the low P content in herbage (0·74–1·19 g kg^?1) and high Ca/P ratios during the dry and hot year (of 2001), a dietary P supplement should be considered for cattle grazing rough fescue grassland in drought years. The low K/(Ca + Mg) ratios (<2·2) suggest there is little risk of grass tetany in cattle grazing on this grassland.