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1.
《Communications in Soil Science and Plant Analysis》2012,43(3-4):313-336
Abstract Loss of soil‐water saturation may impair growth of rainfed lowland rice by restricting nutrient uptake, including the uptake of added phosphorus (P). For acidic soils, reappearance of soluble aluminum (Al) following loss of soil‐water saturation may also restrict P uptake. The aim of this study was to determine whether liming, flooding, and P additions could ameliorate the effects of loss of soil‐water saturation on P uptake and growth of rice. In the first pot experiment, two acid lowland soils from Cambodia [Kandic Plinthaqult (black clay soil) and Plinthustalf (sandy soil)] were treated with P (45 mg P kg?1 soil) either before or after flooding for 4 weeks to investigate the effect of flooding on effectiveness of P fertilizer for rice growth. After 4 weeks, soils were air dried and crushed and then wet to field capacity and upland rice was grown in them for an additional 6 weeks. Addition of P fertilizer before rather than after flooding depressed the growth of the subsequently planted upland rice. During flooding, there was an increase in both acetate‐extractable Fe and the phosphate sorption capacity of soils, and a close relationship between them (r2=0.96–0.98). When P was added before flooding, Olsen and Bray 1‐extractable P, shoot dry matter, and shoot P concentrations were depressed, indicating that flooding decreased availability of fertilizer P. A second pot experiment was conducted with three levels of lime as CaCO3 [to establish pH (CaCl2) in the oxidized soils at 4, 5, and 6] and four levels of P (0, 13, 26, and 52 mg P kg?1 soil) added to the same two acid lowland rice soils under flooded and nonflooded conditions. Under continuously flooded conditions, pH increased to over 5.6 regardless of lime treatment, and there was no response of rice dry matter to liming after 6 weeks' growth, but the addition of P increased rice dry matter substantially in both soils. In nonflooded soils, when P was not applied, shoot dry matter was depressed by up to one‐half of that in plants grown under continuously flooded conditions. Under the nonflooded conditions, rice dry matter and leaf P increased with the addition of P, but less so than in flooded soils. Leaf P concentrations and shoot dry matter responded strongly to the addition of lime. The increase in shoot dry matter of rice with lime and P application in nonflooded soil was associated with a significant decline in soluble Al in the soil and an increase in plant P uptake. The current experiments show that the loss of soil‐water saturation may be associated with the inhibition of P absorption by excess soluble Al. By contrast, flooding decreased exchangeable Al to levels below the threshold for toxicity in rice. In addition, the decreased P availability with loss of soil‐water saturation may have been associated with a greater phosphate sorption capacity of the soils during flooding and after reoxidation due to occlusion of P within ferric oxyhydroxides formed. 相似文献
2.
石灰性土壤交换性盐基组成的测定,通行的方法是采用70%乙醇溶液反复洗盐,再经pH 8.50.1 mol L-1氯化铵-70%乙醇(CH3CH2OH)溶液进行多次交换处理,测定交换液中的K+、Na+、Ca2+、Mg2+浓度。但此方法常常受操作步骤繁琐,以及土壤中碳酸盐的溶解量因多次浸提而增加的困扰,最终导致测定结果偏高。基于上述原因,选择不同浓度、不同pH的NH4OAc和NH4Cl 10种交换剂,对比分析10种交换剂中的碳酸盐溶解度和土壤交换性钙镁含量。结果表明,pH=8.5 1 mol L-1氯化铵-70%乙醇(CH3CH2OH)溶液较适合石灰性土壤交换性盐基的测定。此新方法是先经70%乙醇(CH3CH2OH)溶液洗盐,再用pH8.5 1 mol L-1氯化铵(NH4Cl)-70%乙醇(CH3CH2OH)溶液进行一次性交换处理,然后测定交换液的K+、Na+、Ca2+、Mg2+浓度,简化了操作程序的同时有效抑制了土壤碳酸盐的溶解,降低了测定结果的偏差。 相似文献
3.
为生物炭应用于农田Cd污染的控制及治理提供相关科学依据,研究通过根箱试验,研究棉纤维生物炭对水稻根际和非根际土壤可交换态和不可交换态Cd含量及水稻植株中Cd分配的影响。研究表明:随着棉纤维生物炭的施用量增加,根际和非根际土壤可交换态Cd含量都呈下降趋势,同时不可交换态Cd含量都呈上升趋势。随着棉纤维生物炭的施用量增加,非根际土壤pH值呈逐渐上升趋势。非根际土壤pH值与可交换态Cd含量之间存在显著负相关关系,与不可交换态Cd含量之间存在显著正相关关系。可见,施用棉纤维生物炭可在一定程度上提高非根际土壤pH值,进一步降低了非根际土壤可交换态Cd含量;而根际土壤可交换态Cd含量的下降,主要受棉纤维生物炭的理化性质影响,受土壤pH值影响不大。随着棉纤维生物炭的施用量的增加,水稻各部位Cd含量及累积量都呈现下降趋势,其中籽粒Cd含量的下降幅度最大,为36.57%,根的Cd含量的下降幅度最小,为12.56%。由于茎鞘的生物量和Cd含量都较大,茎鞘中Cd累积量最高,平均为25.44μg plant-1,是籽粒的2.85倍。因此,在进行农田土壤Cd修复的同时,除了要关注农产品Cd污染,还要考虑如何妥善处理大量的富集Cd的农业废弃物,避免产生二次污染风险。 相似文献
4.
本文探讨了铝与铬天青S的最佳显色反应条件。当pH为6.5,在溴化十六烷基三甲铵(CTMAB)和乙醇的存在下,铝与铬天青S形成绿色配合物,最大吸收峰位于635um,表观摩尔吸光系数为1.65×105L/mol·cm,铝含量在0~0.24μg/mL范围内符合比耳定律。在本实验条件下,该方法具有良好的选择性,应用于植物和土壤水中铝的测定,结果满意。 相似文献
5.
Exchangeable potassium and potassium balances in organic crop rotations on a coarse sand 总被引:3,自引:0,他引:3
Abstract. Crops on sandy soils (<5% clay) are exposed to K deficiency due to the small release and high leaching losses of K. Reliable tools are needed to improve the K management in cropping systems with limited K input, such as organic farming where import of nutrients are restricted according to the EC regulations. We investigated K balances and exchangeable K (Kexch ) changes in an organic crop rotation experiment. Potassium leaching decreased from 42 kg ha−1 in 1998/99 to 21 kg ha−1 in 2000/01 as an average of a crop rotation (spring barley, grass-clover, winter wheat and pea/barley) with manure application and without catch crops. In the same period, spring Kexch decreased from 5.0 to 3.0 mg K 100 g soil−1 (0–20 cm). The retention of the straw K left in the field after harvest increased with decreasing levels of Kexch . The cereal crops did not respond to K application but in the pea/barley mixture the pea yield increased by 46%. The concordance between measured K balances and changes in Kexch was weak. Exchangeable K is suitable as a tool for K management on a rotational basis, and a Kexch above 3 mg 100 g soil−1 in the autumn should be avoided to minimize K leaching. 相似文献
6.
Common bean (Phaseolus vulgaris L.) proved to be very sensitive of low pH (4.3), with large genotypic differences in proton sensitivity. Therefore, proton toxicity did not allow the screening of common bean genotypes for aluminium (Al) resistance using the established protocol for maize (0.5 mM CaCl2, 8 μM H3BO3, pH 4.3). Increasing the pH to 4.5, the Ca2+ concentration to 5 mM, and addition of 0.5 mM KCl fully prevented proton toxicity in 28 tested genotypes and allowed to identify differences in Al resistance using the inhibition of root elongation by 20 μM Al supply for 36 h as parameter of Al injury. As in maize, Al treatment induced callose formation in root apices of common bean. Aluminium‐induced callose formation well reflected the effect of Ca supply on Al sensitivity as revealed by root‐growth inhibition. Aluminum‐induced callose formation in root apices of 28 bean genotypes differing in Al resistance after 36 h Al treatment was positively correlated to Al‐induced inhibition of root elongation and Al contents in the root apices. However, the relationship was less close than previously reported for maize. Also, after 12 h Al treatment, callose formation and Al contents in root apices did not reflect differences in Al resistance between two contrasting genotypes, indicating a different mode of the expression of Al toxicity and regulation of Al resistance in common bean than in maize. 相似文献
7.
8.
沸石复混肥对油菜苗期养分吸收、产量及土壤性状的影响 总被引:1,自引:0,他引:1
在盆栽条件下,比较了不同沸石含量的沸石复混肥对盆栽油菜苗期不同阶段N、P、K养分吸收量,油菜籽产量及土壤性状的影响.结果表明:沸石复混肥处理与对照复混肥比较,在苗期的前2个月,油菜吸收的N、P、K均为前者大于后者,而在第3个月开始,为后者大于前者.从整个苗期来看,相比复混肥对照,沸石复混肥处理的油菜N、P、K养分吸收量均有所下降,其中磷吸收量随沸石复混肥中沸石比例的增大而明显下降.沸石能减轻土壤酸化程度,提高土壤pH值,降低EXC-Mn.沸石在复混肥中的比例以10%~15%的含量较为合适,相比对照复混肥,增产可达9.7%. 相似文献
9.
10.
Sorghum [(Sorghum bicolor L.) Moench] is a highly productive crop plant, which can be used for alternative energy resource, human food, livestock feed or industrial purposes. The biomass of sorghum can be utilized as solid fuel via thermochemical routes or as a carbohydrate substrate via fermentation processes. The plant has a great adaptation potential to drought, high salinity and high temperature, which are important characteristics of genotypes growing in extreme environments. However, the climate change in the 21st century may bring about new challenges in the cultivated areas. In this review, we summarize the most recent literature about the responses of sorghum to the most important abiotic stresses: nutrient deficiency, aluminium stress, drought, high salinity, waterlogging or temperature stress the plants have to cope with during cultivation. The advanced molecular and system biological tools provide new opportunities for breeders to select stress‐tolerant and high‐yielding cultivars. 相似文献