Soil Nutrient Variance by Slope Position in a Mollisol Farmland Area of Northeast China

In order to generate scientifically-based comparative information to improve fertilization efficiency and reduce nutrient loss, 610 samples of 122 soil profiles were collected at the 0–60 cm depth to compare soil nutrient contents including soil organic matter(SOM), total nitrogen(TN), total phosphorus(TP), available phosphorus(AP), and available potassium(AK) among different slope positions in a Mollisol farmland area of Northeast China. The contents of SOM and TN typically decreased with increased soil depth at back and bottom slope. Soil loss and deposition tended to decrease SOM and TN at the 0–20 cm soil depth on both the back slope and the slope bottom. The TP firstly decreased from 0–20 cm to 30–40 cm, and then not constantly increased at the back slope and the bottom slope. Due to the characteristics of soil nutrients and crop absorption, the contents of both AP and AK were typically the highest at the summit, followed by the slope bottom and the back slope in the 0–20 cm layer. Generally, in order to sustain the high soil productivity and protect the environment, attention should be paid to soil conservation on back slope; in addition, additional N and P fertilizer is necessary on the back slope.

Effects of recovery time after fire and fire severity on stand structure and soil of larch forest in the Kanas National Nature Reserve, Northwest China

Forest recovery may be influenced by several factors, of which fire is the most critical.However, moderate-and long-term effects of fire on forest recovery are less researched in Northwest China.Thus, the effects of different forest recovery time after fire(1917(served as the control), 1974, 1983 and 1995) and fire severities(low, moderate and high) on larch(Larix sibirica Ledeb.) forest were investigated in the Kanas National Nature Reserve(KNNR), Northwest China in 2017.This paper analyzed post-fire changes in stand density, total basal area(TBA), litter mass, soil organic carbon(SOC) and soil nutrients(total nitrogen, total phosphorus and total potassium) with one-way analyses of variance.Results indicate that litter mass, TBA, SOC and soil nutrients increased with increasing recovery time after fire and decreasing fire severity, while the stand density showed an opposite response.The effects of fire disturbance on SOC and soil nutrients decreased with increasing soil depth.Moreover, we found that the time of more than 43 a is needed to recover the litter mass, TBA, SOC and soil nutrients to the pre-fire level.In conclusion, high-severity fire caused the greatest variations in stand structure and soil of larch forest, and low-severity fire was more advantageous for post-fire forest stand structure and soil recovery in the KNNR.Therefore, low-severity fire can be an efficient management mean through reducing the accumulation of forest floor fuel of post-fire forests in the KNNR, Northwest China.

Heterogeneity of Soil Nutrients:A Review of Methodology,Variability and Impact Factors

Soil nutrient heterogeneity highly correlates to plant growth and development of environmen-tal quality.In order to better understand nutrient cycling,heterogeneity’of soil nutrients and their driving mechanism in different land use types were summarized from 1945 to 2016.By grouping keywords indexed in the titles of articles from the data base of Web of Science,two hundred and thirty’one publications related to our topics were used for analysis.Soil sampling and statistical method were compared,and spatial dependence and the impact factors for soil organic matter(SOM),Nitrogen(N),Phosphorus(P)and Potassium(K).The results showed that soil nutrient heterogeneity was influenced by different factors at different scales.The spa-tial dependence of SOM,N and P were mainly at the moderate level(48.9-59.0%)and strong level(33.3-42.2%),while for K was at strong level(63.6-84.6%)and moderate level(15.4-36.4%).This was mainly influenced by topography,soil loss,weather condition,parent materi-al,soil type,soil texture,land use,human activities,soil moisture,mineral element,soil struc-ture,animal and plant.These impact factors were summarized separately,and the influence of factors at different spatiotemporal scales was discussed.At the end of the review,the ideas for further research were postulated.

Spatiotemporal Changes in Soil Nutrients:A Case Study in Taihu Region of China

The accurate assessment of the spatiotemporal changes in soil nutrients influenced by agricultural production provides the basis for development of management strategies to maintain soil fertility and balance soil nutrients. In this paper, we combined spatial measurements from 2 157 soil samples and geostatistical analysis to assess the spatiotemporal changes in soil organic carbon （SOC）, total nitrogen （TN）, available phosphorus （AP） and available potassium content （AK） from the first soil survey （in the 1980s） to the second soil survey （in the 2000s） in the Taihu region of Jiangsu Province in China. The results showed that average soil nutrients in three soil types all exhibited the increased levels in the 2000s （except for AK in the yellow brown soil）. The standard deviation of soil nutrient contents increased （except for TN in the paddy soil）. Agricultural production in the 20 years led to increases in SOC, TN, AP and AK by 74, 82, 89 and 65%, respectively, of the Taihu areas analyzed. From the 1980s to 2000s all the nugget/sill ratios of soil nutrients indices were between 25 and 75% （except for AK in the yellow brown soil in the 2000s）, indicating moderate spatial dependence. The ratio of AP in the yellow brown soil in the 2000s was 88.74%, showing weak spatial dependence. The spatial correlation range values for SOC, TN, AP and AK in the 2000s all decreased. The main areas showing declines in SOC, TN and AP were in the northwest. For AK, the main region with declining levels was in the east and middle of western areas. Apparently, the increase in soil nutrients in the Taihu region can be mainly attributed to the large increase in fertilizer inputs, change in crop systems and enhanced residues management since the 1980s. Future emphasis should be placed on avoiding excess fertilizer inputs and balancing the effects of the fertilizers in soils.

Regulating Effect of Exogenous Silicon on Soil Fertility in Paddy Fields

In order to explore the effects of different silicon preparations on the soil fertility of paddy fields,a pot experiment with Dongnong 427 was carried on.Different types of silicon preparations,including Si-50-G,Si-60-G,Si-RH,Si-50 and Si-60,were sprayed on the leaves of rice at the tillering stage,and CK was set in the control stage.The contents of alkali nitrogen,available phosphorus,available potassium and available silicon in soil were determined in the tillering stage,booting stage and maturity stage of rice.The results showed that spraying different silicon preparations at the tillering stage could promote the activation and release of soil available nutrients in different degrees.

Application of a Soil Nutrient Measuring Instrument in Vegetable Seedling Substrate

[Objective] The aim was to find an efficient method to measure available nitrogen, phosphorus and potassium content in vegetable seedling substrate. [ Method] The suitable dosage of leaching agent, ratio of the substrate to water and leaching time for the detection of nutrient contents in the substrate by a soil nutrient measuring instrument were discussed firstly, and then the results of nutrient contents measured by the soil nutrient measuring instrument were compared with that by conventional approaches. [ Result] In compadson with the conventional methods, the av- erage content of available nitrogen measured by the soil nutrient measuring instrument was slightly higher, while the average content of available phosphorus measured by the instrument was lower; the average content of available potassium measured by the instrument was close to that by the conventional method. [ Conclusion] This study could provide us a new method to detect available nitrogen, phosphorus and potassium content in seedling substrate efficiently.

How silicon fertilizer improves nitrogen and phosphorus nutrient availability in paddy soil?

In order to reveal the mechanism of silicon(Si)fertilizer in improving nitrogen(N)and phosphorus(P)nutrient availability in paddy soil,we designed a series of soil culture experiments by combining application of varying Si fertilizer concentrations with fixed N and P fertilizer concentrations.Following the recommendations of fertilizer manufacturers and local farmers,we applied Si in concentrations of 0,5.2,10.4,15.6,and 20.8μg/kg.At each concentration of added Si,the availability of soil N and P nutrients,soil microbial activity,numbers of ammonia-oxidizing bacteria and P-decomposing bacteria which means that the organic P is decomposed into inorganic nutrients which can be absorbed and utilized by plants,and urease and phosphatase activity first increased,and then decreased,as Si was added to the soil.These indicators reached their highest levels with a Si application rate of 15.6μg/kg,showing values respectively 19.78%,105.09%,8.34%,73.12%,130.36%,28.12%,and 20.15%higher than those of the controls.Appropriate Si application(10.4 to 15.6µg/kg)could significantly increase the richness of the soil microbial community involved in cycling of N and P nutrients in the soil.When the Si application rate was 15.6μg/kg,parameters for characterizing microbial abundance such as sequence numbers,operational taxonomic unit(OTU)number,and correlation indices of microbial community richness such as Chao1 index,the adaptive coherence estimator(ACE)index,Shannon index,and Simpson index all reached maximum values,with amounts increased by 14.46%,10.01%,23.80%,30.54%,0.18%,and 2.64%,respectively,compared with the control group.There is also a good correlation between N and P mineralization and addition of Si fertilizer.The correlation coefficients between the ratio of available P/total P(AP/TP)and the number of ammonia-oxidizing bacteria,AP/TP and acid phosphatase activity(AcPA),AP/TP and the Shannon index,the ratio of available N/total amount of N(AN/TN)and the number of ammoniated bacteria,and AN/TN and AcPA were 0.9290,0.9508,0.9202,0.9140,and 0.9366,respectively.In summary,these results revealed that enhancement of soil microbial community structure diversity and soil microbial activity by appropriate application of Si is the key ecological mechanism by which application of Si fertilizer improves N and P nutrient availability.

Activation Effect of Hydrochemical Energy in Regenerative Agriculture on Nutrients of Arsenic Sandstone

[Objectives]To study the activation effect of hydrochemical energy in regenerative agriculture on the nutrients of arsenic sandstone.[Methods]Starting from common environmental factors,moisture,it studied the mechanism of the release and activation of N,P,K nutrient elements in arsenic sandstone under different dry and wet environments.[Results]Water played a positive role in activating soil elements.Under the conditions of long-term dryness and alternating dry and wet conditions,the content of total nitrogen,available phosphorus and available potassium coexisted in the 210 d of culture and the element absorption and release,but the overall trend was increasing;under long-term flooding conditions,the content of total nitrogen and available potassium showed an overall increasing trend during the 210 d of culture,but the content of available phosphorus decreased.[Conclusions]Water plays a positive effect on activating soil elements.The research results are expected to provide a certain reference for the application research of water in regenerative agriculture.

外源添加物对不同土地利用方式下土壤肥力的影响

本研究旨在探讨不同土地利用方式(林地、水田和旱田)下,外源添加物对土壤肥力的影响。通过在3种土地利用方式的土壤样品中分别添加生石灰(1 g/kg)、黄腐酸(10 g/kg)、鱼塘底泥(250 g/kg)和生物炭(15 g/kg)4种外源添加物,分析其对土壤碱解氮、速效磷和速效钾含量的影响。结果显示,在相同外源添加物条件下,土壤碱解氮含量呈旱田>林地>水田的趋势,速效磷含量呈耕作层水田>旱田>林地、犁底层旱田>水田>林地的趋势,速效钾含量无明显规律。具体而言,生石灰对碱解氮无显著影响,但使速效磷平均增加14.87%,速效钾平均减少6.19%。黄腐酸对碱解氮含量影响不大,却导致速效磷平均下降16.36%和速效钾平均下降12.94%。鱼塘底泥显著提高了林地、水田和旱田的土壤速效养分,其中碱解氮平均增加57.68%,速效磷平均增加170.16%,速效钾平均增加20.05%,这表明鱼塘底泥不仅直接提供速效养分,还能促进微生物生长,间接提升土壤肥力。生物炭对碱解氮含量影响不显著,但显著增加了各土样的速效磷和速效钾含量,平均增幅分别为89.80%和65.02%。综上所述,4种外源添加物对不同土地利用方式下的土壤肥力有显著差异,其中生物炭和鱼塘底泥的施用对提高土壤肥力尤为有效。

黑龙江和吉林典型地区土壤肥力检测与评价

为掌握黑龙江和东北地区土壤养分资源现状及存在的问题,于黑龙江省大庆市杜尔伯特蒙古族自治县(杜蒙)、吉林省松原市扶余市(扶余)、吉林省长春市九台区(九台)三个地区玉米田地进行土壤肥力情况调查,采样分析土壤中有机质、硝态氮、有效磷、速效钾等指标的质量分数,以及土壤水分和pH值。结果表明,杜蒙土壤有机质含量平均值为20.7 g/kg。扶余土壤硝态氮含量平均值为50.30 mg/kg,速效钾含量平均值为215.89 mg/kg。九台土壤有效磷含量平均值为51.29 mg/kg。研究结果能为黑龙江和吉林地区玉米作物种植施肥管理提供依据和数据支持。

Environmental constraints on the inter-genus variation in the scaling relationship between leaf nitrogen and phosphorus concentrations

Aims The scaling relationship between nitrogen(N)and phosphorus(P)concentrations([N]and[P],respectively)in leaves manifests plants’relative investment between the two nutrients.However,the variation in this relationship among taxa as well as its causes was seldom described.Methods The analysis was based on a dataset including 2483 leaf samples from 46 genera of angiosperm woody plants from 1733 sites across China.We calculated the leaf N–P scaling exponent(βL)with an allometric equation([N]=α[P]β),for each genus,respectively.We then performed phylogenetic path analyses to test how the climate and soil niche conditions of these genera contributed to the inter-genus variation inβL.Important Findings The genera living with lower soil P availability presented a more favoured P uptake relative to N,as shown by the higherβL,suggesting a resistant trend to P limitation.Additionally,genus-wiseβL was positively correlated with soil N–P scaling exponents(β_(S)),implying that the variation in leaf nutrients is constrained by the variability in their sources from soil.Finally,climatic factors including temperature and moisture did not affectβL directly,but could have an indirect influence by mediating soil nutrients.Phylogeny did not affect the inter-genus variation inβL along environmental gradients.These results reveal that the trade-off between N and P uptake is remarkably shaped by genus niches,especially soil nutrient conditions,suggesting that theβL could be considered as a functional trait reflecting characteristics of nutrient utilization of plant taxa in response to niche differentiation.

不同氮磷钾肥对土壤pH和镉有效性的影响

采用土壤培养方法研究了不同氮、磷、钾肥对土壤pH和镉有效性的影响。结果表明,在培养60 d时,所有氮肥处理均降低了土壤pH,增加了Cd的提取量;但高量尿素和氯化铵处理土壤pH降低最多,提取的Cd也最多;硫酸铵提取的Cd较对照增加最小。所有磷肥处理均引起土壤pH小幅降低,但对土壤Cd提取量的影响以普钙稍大。3种钾肥处理均降低了土壤pH,其中氯化钾在0 d时提取的Cd在所有钾肥处理中为最高,其提取能力15 d后逐渐消失,试验结束时所有钾肥处理对Cd提取量均低于对照。本研究进一步表明,在土壤Cd含量处于污染临界值附近或已受Cd污染的土壤上,应避免施用高量的酸性肥料如尿素、氯化铵、普钙,以及其他酸性物料。在常用磷、钾肥中,磷酸二铵和硫酸钾在Cd污染土壤上施用更为适合。

橘园不同施肥方式对N、P、K在土层中分布的影响

以栽培枳砧纽荷尔脐橙的渗漏池内红壤和紫色土为对象,研究尿素和磷酸二氢钾撒施、沟施和浇施后,0～50cm土层中碱解氮、速效磷和速效钾含量变化。结果表明,尿素无论采用何种施肥方式,氮在红壤和紫色土中容易向下迁移;磷酸二氢钾无论采用何种施肥方式,磷在红壤中都极易被固定,各土层中的速效磷含量很低,对土壤速效磷的提高几乎未起作用,而在紫色土中磷的固定作用较弱,撒施后可显著提高土层中速效磷含量,土壤上层的速效磷含量显著高于下层;施用磷酸二氢钾使红壤和紫色土中速效钾含量升高,总体上土壤上层速效钾含量高于土壤下层。另外,还对柑橘园的适宜施肥方法进行讨论。

我国主要低产水稻冷浸田养分障碍因子特征分析

研究我国冷浸田主要分布的7个省份冷浸田土壤样品的养分特征,通过与当地高产田土壤养分特征比较发现:我国冷浸田土壤中有机质含量(13.76～21.52g/kg)和全磷含量(2.78～11.36g/kg)总体高于高产田,部分差异显著(P<0.05);全氮含量(1.39～2.24g/kg)总体略高于高产田,但差异不显著(P<0.05);有效锌含量(4.92～11.03mg/kg)总体高于高产田的含量,且差异显著(P<0.05),表明我国冷浸田的潜在生产力比较高。但是,与高产田相比,我国冷浸田土壤pH值显著偏低(4.47～5.32),致毒因子还原态硫含量(296.12～3 069.33mg/kg)和亚铁含量(160.28～3 786.12mg/kg)却显著偏高(P<0.05),同时,部分地区冷浸田土壤速效磷(1.90～30.20mg/kg)和速效钾(1.30～111.70mg/kg)养分显著缺失(P<0.05),表明这几种养分指标是影响我国冷浸田生产力的重要障碍因子,因此,只要有针对性的改良上述冷浸田养分障碍因子,其必将成为我国粮食生产的巨大战略资源。

缙云山森林土壤速效N、P、K时空特征研究

研究了缙云山森林生态系统内 4个演替阶段群落的土壤速效 N、P、K的时空特征 ,结果表明 :1除灌草丛的速效 K外 ,速效 N、P、K含量在不同群落的土壤剖面上均具有明显的层次性 ,即腐殖质层 (A) >沉积层 (B) >母质层 (C)。 2 A、B两层的速效 N、K含量随群落演替方向升高 ,即灌草丛 <针叶林 <针阔混交林 <常绿阔叶林 ,速效 P含量则为 :针叶林 <针阔混交林 <灌草丛 <常绿阔叶林。 C层速效 N、P、K含量似乎与群落演替规律无必然联系。 3各群落内 A、B层土壤速效 N、P、K含量均表现出明显的季节动态 。

微喷灌水定额对烟田土壤物理性状和养分运移的影响

以不灌水和传统沟灌为对照,研究了不同微喷灌水定额对河南宝丰壤质土壤物理性状和养分运移的影响.结果表明,与传统沟灌相比,微喷可有效控制每次灌水定额,降低土壤容重,微喷定额为24～36 mm,不仅能有效补充土壤水分,又可使土壤湿润层保持在耕层范围内.灌溉后24 h各灌水处理0～30 cm土层中碱解氮含量均高于不灌水,且随着灌水定额的增加,碱解氮含量呈增加趋势,圆顶期则呈现相反的变化,以不灌水最高.传统沟灌水分下渗过深,造成土壤速效养分的淋失,灌水后24 h测定,耕层土壤碱解氮含量低于微喷36 mm处理,速效钾含量低于其他处理,而碱解氮含量在20 cm以下土层、速效钾含量在30 cm以下土层中含量提高.

沈阳市苏家屯区农田土壤有效氮磷钾含量变化的分析

对沈阳市苏家屯区露地和保护地土壤有效氮、磷、钾养分现状进行了调查 ,对露地土壤有效磷、钾在20年间含量变化进行了分析。结果显示 :露地土壤有效氮肥力水平较高 ,全区平均含量为98.96mg·kg-1 ;20年间 ,土壤有效磷含量递增 ,平均含量从1980年的4.96mg·kg-1 上升到2000年的11.61mg·kg-1;土壤有效钾呈递减趋势 ,平均含量从1980年的128.08mg·kg-1下降到2000年的79.90mg·kg-1,平均每年降低1.90%。保护地土壤有效氮、磷、钾含量随使用年限的增加呈上升趋势。

植物物料及其生物炭对酸性土壤的改良

采用室内培养方法结合相关分析和逐步回归分析等方法研究了分别添加15 g/kg、45 g/kg和75 g/kg的椰壳、蔗渣和椰炭、蔗炭对酸性橡胶园土壤的改良效果。结果表明:同对照相比,添加植物物料及其生物炭均显著提高或提高了土壤pH、土壤有机质和速效钾含量,且随着添加量的提升而升高;添加椰壳和蔗渣均显著降低或降低了土壤碱解氮和速效磷含量;添加椰炭15 g/kg、45 g/kg和蔗炭15 g/kg均显著提升了土壤碱解氮含量,而其余椰炭和蔗炭处理降低了土壤碱解氮含量,但除15 g/kg椰炭和15 g/kg蔗炭处理外,其余椰炭和蔗炭处理均提升了土壤速效磷含量,且随着添加量的提升而升高。逐步回归分析表明,主要是植物物料及其生物炭带入土壤中的钠、碳、钙、镁等影响了土壤pH和速效钾、有机质、碱解氮、速效磷含量,且带入土壤中的钠、碳、镁越多,土壤pH、速效钾、有机质和速效磷含量越高,而钙与土壤碱解氮之间则呈反向变化。此外,利用回归分析方程,通过对生物炭得率及带入土壤中相关养分的总量计算可知,椰壳制作为生物炭对土壤pH、速效钾、碱解氮提升效果更好;蔗渣直接施用对土壤pH和速效钾的提升效果更好;椰壳和蔗渣均直接施用更有利于土壤有机质的提升。因此,生产中需根据土壤改良目的确定植物物料的施用方法和施用量。

不同间伐模式下杨农复合系统土壤养分垂直分布特征

以海河低平原杨农复合系统为研究对象,针对4年树龄的杨树进行间伐（Intermediate cutting）处理,通过不同间伐模式下1年后土壤0-200 cm有机质、全氮、速效磷和速效钾含量的测定,初步研究土壤养分的垂直分布特征。结果表明,不同间伐模式下土壤有机质、全氮、速效磷和速效钾含量具有明显的垂直分布特征,其中有机质和全氮自上而下呈现递减趋势,速效磷自上而下呈现U型变化趋势,速效钾自上而下呈现波动趋势。两种杨树间伐模式10 m×2 m和5 m×4 m,与常规（Traditional）5 m×2 m相比,土壤表层（0-20 cm）有机质、全氮、速效磷的含量无显著性差异,速效钾含量有显著性差异。在40-140 cm土层间伐10 m×2 m模式的土壤养分含量显著高于常规5 m×2 m和间伐5 m×4 m,杨树间伐10 m×2 m处理较常规5 m×2 m处理和间伐5 m×4 m处理具有更好的土壤养分保持功能。

内蒙古敖汉旗不同类型防护林的土壤养分特征

在内蒙古敖汉旗选择3种防护林，比较4个深度（0～10、10~20、20~40cm和40~60cm）的土壤有机质、碱解氮、速效磷和速效钾含量。结果表明，杨树×樟子松林的有机质含量最高，柠条和沙棘2种灌木林次之。杨树×樟子松林的碱解氮含量最高，沙棘林次之。杨树×樟子松林的速效磷含量最高，沙棘林次之。杨树×樟子松林的速效钾含量最高，柠条林和沙棘林次之。因此，杨树×樟子松林的土壤养分条件较好，沙棘林次之。这2种防护林可以作为科尔沁沙地的优化防护林类型。