不同有机肥中Cu、 Zn在农田土壤中的有效性与形态归趋

【目的】畜禽粪便有机肥的施用是造成我国农田土壤重金属污染的重要原因之一。本文选用两种典型规模化养殖场畜禽粪便有机肥,研究其在石灰性土壤和酸性土壤上施用1年后Cu、 Zn的有效性和形态归趋,为客观评价畜禽粪便有机肥中重金属进入土壤后的环境行为和生态风险提供理论依据。【方法】采用温室土壤培养试验,在石灰性土壤和酸性土壤上分别设对照(CK)、 施2%鸡粪(CM2%)、 施5%鸡粪(CM5%)、 施与CM2%、 CM5%含等量Cu、 Zn的重金属无机盐溶液(CS2%、 CS5%)、 施2%猪粪(PM2%)、 施5%猪粪(PM5%)、 施与PM2%、 PM5%含等量Cu、 Zn的重金属无机盐溶液(PS2%、 PS5%)9个处理,每个处理设3次重复,在温室条件下培养1年。测定土壤pH值, EDTA提取有效态Cu、 Zn以及采用改进Tessier连续提取法提取的各形态Cu、 Zn的含量,分析鸡粪、 猪粪及等量无机盐溶液中Cu、 Zn进入土壤后的有效性和形态归趋。【结果】施用鸡粪和猪粪1年后,石灰性土壤的pH值降低,酸性土壤的pH值升高,施用5%猪粪时石灰性土壤pH值降低了0.23个单位,酸性土壤pH值升高了0.87个单位。施入鸡粪、 猪粪1年后,石灰性土壤中有效态Zn和酸性土壤中有效态Cu、 Zn含量显著增加,施用5%猪粪时酸性土壤中有效态Cu含量增加了1.95倍,施用5%鸡粪时2种土壤中有效态Cu的含量均显著低于等量无机盐。施用鸡粪和等量无机盐后,2种土壤中交换态和有机结合态Cu的含量显著增加,交换态、 碳酸盐结合态、 有机结合态和铁锰氧化物结合态Zn的含量显著增加; 施用猪粪和等量无机盐后,2种土壤中交换态、 铁锰氧化物结合态和有机结合态Cu的含量显著增加,碳酸盐结合态和铁锰氧化物结合态Zn的含量显著增加。【结论】施用鸡粪、 猪粪提高了石灰性土壤中Zn和酸性土壤中Cu、 Zn的有效性,高用量条件下鸡粪中Cu的有效性低于等量无机盐。1年后, 通过畜禽粪便有机肥带入2种土壤中的Cu 主要以交换态和有机结合态的形式存在,Zn则主要以碳酸盐结合态、 铁锰氧化物结合态和有机结合态的形式存在。2种土壤上有机肥带入的Cu、 Zn转化为铁锰氧化物结合态的比例低于等量无机盐,2种有机肥带入2种土壤中的Cu转化为交换态和有机结合态的比例高于等量无机盐。鸡粪带入的Zn转化为交换态的比例在酸性土壤中低于等量无机盐,但在石灰性土壤中则高于等量无机盐。     

Effect of soil application of nickel on growth,micronutrient concentration and uptake in barley (Hordeum vulgare L.) grown in Inceptisols of Varanasi

A pot experiment was conducted in a glass house on low nickel containing alluvial soil in the Department of Soil Science and Agricultural Chemistry, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, during 2012–13 and 2013–14, to study the response of barley to soil application of nickel (Ni). There were ten treatments of Ni (0, 2.5, 5, 10, 15, 20, 30, 40, 50 and 60 mg kg^?1) studied with recommended dose of fertilizers nitrogen, phosphorus, potassium and sulfur (N:P:K:S :: 40:30:30:20 mg kg^?1).The results showed a significant increase in plant height, number of tillers, chlorophyll content, straw and grain yield, and 1,000 grains weight with application of 10 mg Ni kg^?1 soil during both years of study. The micronutrient concentration and uptake in straw and grain increased with application of <15 mg Ni kg^?1 soil and beyond that declined significantly. Diethylenetriaminepentaacetic acid-extractable micronutrient iron, manganese, copper, zinc and nickel (Fe, Mn, Cu, Zn and Ni) content in soil increased with increasing level of Ni. The maximum urease activity in post-harvest soil was noticed with application of 40 mg Ni kg^?1 soil. The microbial population viz. bacteria, fungi and actinomycetes were higher with 5, 30 and 10 mg Ni kg^?1 soil, respectively.     

Effects of ZnSO4 and Zn‐EDTA applied by broadcasting or by banding on soil Zn fractions and Zn uptake by wheat (Triticum aestivum L.) under greenhouse conditions

Zinc biofortification of staple food crops is essential for alleviating worldwide human malnutrition. Agronomic interventions to promote this should include fertilizer selection and management. A chelated Zn source, Zn‐EDTA, and an inorganic Zn source, ZnSO₄ × 7 H₂O, were applied either by banding or by broadcasting in soil, and Zn fractions in soil and Zn uptake by wheat were determined in a pot experiment. Compared to ZnSO₄ × 7 H₂O, Zn‐EDTA produced higher Zn concentration in grain regardless of application method and even at a lower application rate. Residual Zn fraction was the largest Zn fraction with both ZnSO₄ and Zn‐EDTA amendment. ZnSO₄ banded in soil caused Zn fractions to be restricted to the Zn‐amended soil band and resulted in lower grain Zn concentrations than did broadcast ZnSO₄. Planting wheat slowed Zn fixation by promoting the maintenance of a high concentration of Zn fraction loosely bound to organic matter (LOM‐Zn) in soil. Zn‐EDTA was a better Zn source for Zn biofortification of wheat than was ZnSO₄.     

Localized application of sewage sludge improved plant nitrogen and phosphorus uptake by rhizobox‐grown spring wheat

Sewage sludge (SS) can be used as an alternative fertilizer in agriculture. It is normally broadcasted and plowed into soil, but it is not clear if it has a potential as a placement fertilizer. A rhizobox experiment was conducted to investigate the placement effect of SS and mineral nitrogen (N) fertilizer on shoot and root growth as well as nutrient uptake of spring wheat (Triticum aestivum L.). The treatments included localized SS, mixed SS, localized SS and ammonium, localized ammonium, and a control without addition of SS and ammonium to examine the effect of SS placement and, further, if ammonium co‐localization would enhance the placement effect. The results show that SS fertilization improved soil N and P availability, which significantly increased plant N and P uptake and enhanced shoot growth, while root length was significantly reduced compared to the control. Localized SS increased root proliferation in the placement region, resulting in enhanced uptake of P from the SS patch compared to homogenous application. However, co‐localized application of ammonium with SS significantly depressed plant shoot and root growth. Localized ammonium markedly restricted root proliferation in the placement region and reduced soil pH in both bulk soil and placement region, contributing to decreased nutrient uptake and plant growth.     

Genetic diversity changes and relationships in spring barley (<Emphasis Type="Italic">Hordeum vulgare</Emphasis> L.) germplasm of Nordic and Baltic areas as shown by SSR markers

To examine changes in the level of and pattern in variability in 197 Nordic and Baltic spring barley cultivars over time we used 21 mapped barley simple sequence repeats (SSRs). A total number of 191 alleles were found from 22 SSR loci. The number of alleles per locus ranged from 2 to 23, with average of 8.63 107 alleles were rare (frequency <0.05) among the cultivars and only one allele was frequently observed (frequency >0.95). The gene diversity between loci in Nordic and Baltic material varied between 0.033 and 0.891. Average gene diversity was 0.623. The SSR data separated two-rowed and six-rowed cultivars. According to analysis of molecular variance (AMOVA) differentiation in two-rowed vs six-rowed accounted for 23.6% of the total variation. Overall no significant decrease of average gene diversity over time could be found. However, differences were observed when spring barleys from northern (north of ∼58°) and southern (south of ∼58°) parts of the Nordic and Baltic area were compared. For the southern ecogeographical region significant decrease of genetic diversity was observed in the middle of the 20th century, whereas no significant changes in the northern part were found. We found larger differentiation between modern and old cultivars in the South compared to the ones in North parts of the region. The magnitude of changes in genetic diversity differed also with the country of origin. Danish cultivars had a significant decrease in diversity in the middle of century, whereas changes in Finland, Norway and Sweden were not significant.     

Impact of urease and nitrification inhibitor on NH4+ and NO3− dynamic in soil after urea spring application under field conditions evaluated by soil extraction and soil solution sampling

The application of mineral nitrogen (N) fertilizers is one of the most important management tools to ensure and increase yield in agricultural systems. However, N fertilization can lead to various ecological problems such as nitrate () leaching or ammonia and nitrous oxide emissions. The application of N stabilizers (i.e., inhibitors) combined with urea fertilization offers an effective option to reduce or even prevent N losses due to their regulatory effect on ammonium () and release into the soil. The present field experiment therefore aimed at soil N speciation dynamics after urea spring fertilization (225 kg N ha^?1) in the presence of a urease inhibitor (UI), a nitrification inhibitor (NI), both inhibitors (UI+NI) or when no inhibitor was applied at all. The study focused on the distribution of N species among soil matrix and soil solution. Plant cultivation was completely omitted in order to avoid masking soil N turnover and speciation by plant N uptake and growth dynamics. Application of UI clearly delayed urea hydrolysis in the top soil, but a complete hydrolysis of urea took place within only 10 days after fertilization (DAF). Nitrification was significantly reduced by NI application, leading to higher and lower concentrations in treatments with NI. Due to sorption of to the soil matrix a significantly larger fraction of was always detected in the soil extracts compared to soil solution. However, while in soil extracts the impact of NI application was less apparent and delayed, in soil solution a quick response to NI application was observed as revealed by significantly increased soil solution concentrations of . Because of the “asymmetric” soil phase distribution soil solution was predominant over only initially after fertilization even in inhibitor treatments (≈ 8 to 10 DAF). Nevertheless, inhibitor application tended towards closer ratios of to concentration in soil solution and hence, might additionally affect concentration dependent processes like plant N uptake and root development. Despite cold spring conditions urea application along with UI and/or NI did not indicate a limited supply of plant available and .