Effects of nutrient cycling on grain yields and potassium balance

Soybean-maize rotation is a profitable cropping system and is used under rain fed conditions in north China. Since crop yields have been reported to decrease when K fertilizers are not used, we analyzed the productivity trends, soil-exchangeable and non-exchangeable K contents, and K balance in a continuous cropping experiment conducted in an area with an alfisol soil in the Liaohe River plain, China. The trial, established in early 1990 and continued till 2007, included 8 combinations of recycled manure and N, P, and K fertilizers. In the unfertilized plot, the yields of soybean and maize were 1,486 and 4,124 kg ha⁻¹ respectively (mean yield over 18 years). The yields of both soybean and maize increased to 2,195 and 7,476 kg ha⁻¹, respectively, in response to the application of inorganic N, P, and K fertilizers. The maximum yields of soybean (2,424 kg ha⁻¹) and maize (7,790 kg ha⁻¹) were obtained in the plots under treatment with N, P, and K fertilizers and recycled manure. K was one of the yield-limiting macronutrients: regular K application was required to make investments in the application of other mineral nutrients profitable. The decrease in the yields of soybean and maize owing to the absence of K application averaged 400 and 780 kg ha⁻¹, respectively. Soybean seed and maize grain yields significantly increased with the application of recycled manure. For both these crops, the variation coefficients of grain were lower with treatments that included recycled manure than without treatment. After 18 years, the soil-exchangeable and non-exchangeable K concentrations decreased; the concentrations in the case of treatments that did not include K fertilizers were not significantly different. Treatment with N, P, and K fertilizers appreciably improved the fertility level of the soil, increased the concentration of soil-exchangeable K, and decreased the non-exchangeable K concentration. In soils under treatment with N, P, and K fertilizers and recycled manure, the soil-exchangeable and non-exchangeable K levels in the 0–20 cm-deep soil layer increased by 34% and 2%, respectively, over the initial levels. Both soil-exchangeable and non-exchangeable K concentrations were the highest with on treatment with N, P, and K fertilizers and recycled manure, followed by treatment with N, P, and K fertilizers. These concentrations were lowest in unfertilized soils; the other treatments yielded intermediate results. The results showed a total removal of K by the crops, and the amount removed exceeded the amount of K added to the soil; in treatments that did not include K fertilizers, a net negative K balance was observed, from 184 to 575 kg ha⁻². The combined use of N, P, and K fertilizers and recycled manure increased the K content of the 0–20 cm-deep soil layer by 125% compared to the increase obtained with the application of N, P, and K fertilizers alone. The results clearly reveal that current mineral fertilizer applications are inadequate; instead, the annual application of recycled manure along with N, P, and K fertilizers could sustain future yields and soil productivity.     

茜素红褪色动力学光度法测定痕量钴

在pH 8.0的氨-氯化铵介质中,以聚氧乙烯醚-200（PEG-200）为活化剂,Co催化溴酸钾氧化茜素红褪色,建立了动力学光度法测定痕量Co的新方法。该方法检出限为2.0×10-7g/L;线性范围0.01~0.21μg/50 mL;最大相对标准偏差为4.3%。该法用于湖水及生产排水的测定,结果满意;加标回收率在96.0%~105.0%。     

降低碘耗的途径

碘盐生产过程中碘酸钾的添加系统、碘酸钾添加控制办法与碘酸钾的添加稳定性,对于保证碘盐合格率、降低生产成本有重要影响。本文从这三个方面进行分析,以期对从事加碘工作的同行有所帮助。     

Synthesis and thermal decomposition of potassium tetraamidoboranealuminate,K[Al(NH2BH3)4]

A new potassium tetraamidoboranealuminate, K[Al(NH₂BH₃)₄], has been synthesized by a mechanochemical reaction between KAlH₄ and NH₃BH₃. The compound, K[Al(NH₂BH₃)₄], crystallizes in a triclinic unit cell with space group symmetry P?1. The crystal structure consists of [K(NH₂BH₃)₆]^5? octahedra which facilitate the bridging between K⁺ in 1D chains, while also bridging K⁺ to Al³⁺ to connect the 1D chains in a 3D network. Thermal analysis reveals that K[Al(NH₂BH₃)₄] decomposes in two exothermic steps at T ～ 94 and 138 °C and releases primarily hydrogen. The total gas release amounts to ～6.0 wt% H₂. The decomposition products are investigated ex situ by powder X-ray diffraction, infrared spectroscopy, and ¹¹B and ²⁷Al NMR and identified as KBH₄ and amorphous phases, possibly BN₃, N₂BH, and/or NBH₂ whereas aluminum is found in four-, five-, and six-fold coordination. Unfortunately, the decomposed sample shows no hydrogen absorption at T = 260 °C and p(H₂) = 110 bar.     

Effect of waterglass on water stability of potassium magnesium phosphate cement paste

This paper studied the influence of waterglass on the early water stability of potassium magnesium phosphate cement (MKPC). Mass loss and residual strength were used to reflect the water stability of MKPC pastes exposed to different curing conditions. Experimental results indicated that the addition of waterglass could accelerate early hydration of MKPC, reduce the crystallinity of hydration products, and improved the pore structures significantly. The early water stability of MKPC was greatly improved due to the significant decreased dissolution of hydration products and pore volume of hardened MKPC.     

氮磷钾肥配施对不同品种大白菜硝酸盐累积的影响

通过采用二次饱和D-最优回归设计(311B方案),对氮磷钾肥配施与大白菜硝酸盐累积之间的关系进行研究,建立了能调控大白菜硝酸盐含量的施肥模型。分析表明,不同品种大白菜硝酸盐含量与施肥有很大关系,但品种间存在着较大的差异。在相同施肥处理下,绿星80大白菜硝酸盐含量略低于五福菜的硝酸盐含量。不同品种大白菜硝酸盐累积量和硝酸还原酶活性具有很大的相关性,可作为大白菜体内硝酸盐累积的一项指标。     

云南省主要地质背景区铜、锰、锌、镁、钾在岩石-土壤-饲料系统的分布与迁移规律研究

对云南省6个主要地质背景区的土壤、岩石和饲料样品的铜、锰、锌、镁和钾元素进行测定分析。结果表明:玄武岩和碳酸盐岩红壤区土壤和饲料钾、镁、锌、锰和铜元素含量较丰富;碳酸盐岩、碎屑岩和玄武岩混合型黄红壤区居中;而由碎屑岩和变质岩发育的土壤区土壤和饲料钾、镁、锌、锰和铜元素最低。饲料中钾、镁、锌、锰和铜的含量受地质背景值,特别是土壤中元素的丰度的影响不大。     

皖南红黄壤地区连续施用磷钾肥对油菜产量、养分吸收及土壤肥力的影响

在皖南红黄壤地区利用大田试验研究了连续施用磷钾肥对油菜产量、养分吸收和土壤肥力的影响。结果表明:在施用氮肥的基础上合理配施磷钾肥,促进了油菜的生长发育,提高了油菜植株的养分含量和养分吸收量,从而显著增加了油菜的产量,并且磷肥的增产效应大于钾肥效应,三季油菜平均产量以处理P90K120最高,达到了1968.7 kg hm-2;同时连续施用磷钾肥能够改善土壤养分含量,显著提高了土壤速效钾、速效磷含量,与试验前土壤相比,速效磷增加了14.83~20.2 mg kg-1,速效钾增加了69.51~109.61 mg kg-1。     

硫酸钾生产工艺的选择

本文论述了我省发展Ｋ２ＳＯ４生产的重要性，介绍了目前Ｋ２ＳＯ４的主要生产方法，着重指出用磷石膏和氯化钾制造Ｋ２ＳＯ４的经济意义和环境效益．