Soil Aggregates, Organic Matter, and Labile C and N Fractions after 37 Years of N, P and K Applications to an Irrigated Subtropical Soil under Maize-Wheat Rotation

Abstract： Physical, chemical and biological soil properties in surface （0-5 cm） and subsurface soil （5-15 cm） were determined in a field experiment conducted with seven treatments consisted of different combinations of fertilizer N （0, 100 and 200 kg N ha^-1）, P （0, 22 and 44 kg P2O5 ha^-1） and K （0, 41 and 82 kg K2O ha^-1） applied both to summer-grown maize （Zea mays L.） and winter-grown wheat （Triticum aestivum L.） crops continuously for 37 years under irrigated subtropical conditions. Application of N, P and K significantly increased water stable aggregates and had profound effects in increasing the mean weight diameter as well as the formation of macro-aggregates, which were highest in both surface （81%） and subsurface （74%） soil layers with application of 100 kg N ＋ 22 kg P2O5 ＋ 41 kg K2O ha^-1 （N100P22K41）. The N100P22K41 treatment also enhanced total organic C （TOC） from 4.4 g kg^-1 in no-NPK control to 4.8 g kg^-1in surface layer and from 3.3 to 4.1 g kg1 in subsurface layer leading to the 20% higher TOC stocks in 0-15 cm soil. The labile C and N fractions such as water soluble C, particulate and light fraction organic matter, potentially mineralizable N and microbial biomass were also highest under the optimized balanced application of N100P22K41. Relatively higher increase in all labile fractions of C and N as proportion of TOC and total N, respectively suggested that these are potential indicators to reflect changes in management practices long before changes in TOC and TN are detectable. These results demonstrated that optimized balanced application of N, P and K is crucial for improving soil health ensuring long-term sustainability of farming systems in semiarid subtropical soils.

Effects of N, P and K on Output and Nutrient Cycle of Vegetables in Greenhouses

ObjectiveThe aim was to increase farmers’ income and reduce the waste of fertilizer by exploring effects of N, P and K fertilizations on vegetable yields and the accumulation of N, P and K in vegetable and soils. MethodThe fertilization tests were conducted on tomato, cauliflower and celery in greenhouses. ResultWhen N, P and K were not applied in tomato, cauliflower or celery, the yields reduced in 6.0%-13.8% and total annual income reduced by 39 220, 36 902 and 22 023 yuan/hm 2 respectively, suggesting that N, P and K are limiting factors of yield. The absorbed N amounts of tomato and cauliflower were higher compared with celery; the absorbed P amount of cauliflower was higher compared with tomato and celery; the absorbed K amount of tomato was the highest, followed by celery and cauliflower. The absorbed N in tomato fruit was lower than that of cauliflower and the absorbed N amount of other parts of tomato was also lower. Furthermore, the absorbed amounts of P and K by tomato and cauliflower fruits were higher than it absorbed by the other parts, especially the absorbed of K was significantly high. Total absorbed amounts of N, P and K from high to low were cauliflower, tomato and celery. After harvesting of tomato, cauliflower and celery, N, P and K in soils were all higher compared with soils before planting. Influenced by fertilizers, residual N content in soils grown with tomato and residual P content in soils grown with celery both doubled compared with base soils. Cauliflower plants were not applied with organic fertilizer, and residual N and K contents in soils were lower compared with tomato and celery. ConclusionResidual P content in soils is higher, which is a kind of waste and would cause pollution on soils. It is necessary to improve the proportion of organic and inorganic fertilizers in fertilization.

Effects of N,P and K Fertilizers on Growth of Clover Nitrogen-fixing Rhizobia and Soil Fertility after Plantation

In order to develop organic rice and increase paddy soil fertility by cloverorganic rice rotation, the effects of N, P and K fertilizers on growth of clover nitrogen-fixing rhizobia and soil fertility after plantation were investigated, thereby providing certain reference for reasonable cultivation of clover and improvement of soil fertility. A two-year experiment was conducted from 2012 to 2013. The clover was cultivated after rice every year, and different levels of N, P and K fertilizers were applied before winter. In the treatment group, no fertilizer was applied. The effects of different fertilizers and different application amounts on clover yield, nitrogen-fixing rhizobia quantity, nitrogen-fixing rhizobia weight and soil fertility after plantation were analyzed. The results showed that the application of N, P and K fertilizers in the early stage had significantly effect on the growth of clover. When the application amount of N fertilizer was 75 kg/hm^2（N 46%）, the clover yield, nitrogen-fixing rhizobia quantity and nitrogen-fixing rhizobia weight were highest. The soil nitrogen content after plantation increased with the increase of the application amount of N fertilizer, while the P and K content decreased and then increased with the increased application amounts. Soil available P content increased with the increased application amounts of N and P fertilizers, but it did not change significantly with the increased application amount of K fertilizer. Soil available K content increased first and then decreased with the increased application amounts of N and P fertilizers.When the application amounts of N and P fertilizers were 150（N 46%） and 300（P_2O_5 12%） kg/hm^2, soil available K content reached the maximum. Soil organic matter content increased with the increased application amounts of N, P and K fertilizers. Therefore, in the cultivation of clover, appropriate application of N, P and K fertilizers in the early stage can improve clover yield and soil fertility.

Assessment of Soil C and N Stocks and Fractions across 11 European Soils under Varying Land Uses

In this study, we measured the stocks and pool sizes of soil organic carbon (SOC) and total soil nitrogen (TN), and their natural 13C and 15N abundance across a wide range of temperate European ecosystems. The objectives were to examine any distinct isotope patterns with land use or climate, and how C and N in these different ecosystems are distributed among soil organic matter (SOM) fractions to better predict soil C and N dynamics and longer term persistence. Soils were sampled to 30 cm depth at 11 sites of the Nitro Europe (NEU) network and included four forests, three grasslands and four croplands. Surface soil samples were fractionated using a combined size-density fractionation protocol separating light (LF) from heavy particulate organic matter (hPOM) by density and silt-from-clay-associated SOM by size. Down-profile natural abundance 15N patterns pointed towards a closed N cycle in the forest sites, while 13C patterns suggested differences in plant water use efficiency across the C3 grassland sites. The forests and grassland sites stored the majority of surface SOC and TN in the LF and hPOM pools. Sustained sequestration of C and N in these rather labile pools will rely on management practices that minimize soil disturbance and increase C input. We also found that the mineral fraction (silt and clay) in the cropland soils stored less C and N per unit of fraction mass compared to the forests and grasslands, which points towards a lower mineral-OM stabilization efficiency of cropland soils. Finally, our study revealed total POM (LF plus hPOM) as a strong predictor of SOC and TN differences, particularly among the non-cropped sites. This study shows that these sites, independent of soil type and climate, store a large fraction of C and N in POM pools that are particularly vulnerable to soil disturbance such as caused by land use change.

专用缓释肥料对黄瓜产量品质及N,P,K养分吸收利用的影响

采用土培试验研究了黄瓜专用缓释肥对黄瓜产量品质及N,P,K养分吸收利用、土壤酶活性的影响.结果表明:2种专用缓释肥(CSRF1和CSRF2)显著提高了黄瓜果实干物质量和总干物质量,CSRF1和CSRF2处理黄瓜果实干物质量较CCF,MSRF,OCF处理分别增加了23.3%~37.2%和16.5%~31.6%.2种专用缓释肥(CSRF2和CSRF1)提高了黄瓜果实的维生素C质量分数和氨基酸的质量分数,降低了硝酸盐质量分数.黄瓜根、茎、叶和果实的N,P,K养分质量分数均以CSRF2最高.黄瓜N,P,K积累量从大到小依次为CSRF2、CSRF1、MSRF、CCF、OCF,专用缓释肥处理的N,P,K积累量较MSRF,CCF和OCF处理分别提高了27.45%~46.55%,33.17%~56.20%和67.61%~102.13%.与普通复合肥相比,2种专用缓释肥处理的N,P,K相对养分利用效率分别增加了18.53%~24.20%,19.27%~20.02%和18.54%~35.69%.

硝态N累积与菠菜有机N形成及P、K吸收的关系

在低N(0.3g·kg-1土)和高N(0.6g·kg-1土)2个水平下,采用土壤盆栽试验,研究了30个菠菜品种硝态N累积情况及其与植株生长,有机N形成,P、K吸收的关系。结果表明:施N水平低时,30个菠菜品种的硝态N含量与生长量、有机N总量和P、K吸收量之间均无显著的相关关系;高N时,菠菜品种间硝态N含量表现出显著的差异,硝态N含量最高与最低相差242mg·kg-1,与生长量、有机N总量和P、K吸收量之间亦呈极显著正相关关系。

天水市麦积区经济林种植土壤中NPK的空间变异分析

经济林产业对于地方经济的发展和生态环境的保护具有重要作用。为了实现经济林木的科学种植,选择对经济林木种植影响较大的土壤中的N、P、K因子与区划图(即经济林分布图),结合少量的地面调查数据,借助于变异分析、3S技术和空间插值方法,对甘肃省天水市麦积区经济林种植区土壤中的N、P、K含量进行了定量分析和预测研究。结果表明:苹果、葡萄、花椒、樱桃、梨、桃、杏、山楂、核桃、柿子等不同种植区土壤中N、P、K的差异比较大,且其比例严重失调;土壤中N、P的空间相关性很弱,说明受外界因素的影响比较小;土壤中的K具有很强的空间相关性,说明受外界因素的影响比较大,这主要与草木灰中含钾量较高有关;麦积区经济林种植过程中N、P、K的施用还没有可以参照的统一的地方标准,随机性很大。

Effects of the combined application of organic and chemical nitrogen fertilizer on soil aggregate carbon and nitrogen:A 30-year study

To understand the long-term effects of combined organic and chemical nitrogen fertilization on soil organic C(SOC) and total N(TN), we conducted a 30-year field experiment with a wheat–maize rotation system on the Huang-HuaiHai Plain during 1990–2019. The experimental treatments consisted of five fertilizer regimes: no fertilizer(control), chemical fertilizer only(NPK), chemical fertilizer with straw(NPKS), chemical fertilizer with manure(NPKM), and 1.5 times the rate of NPKM(1.5NPKM). The NPK, NPKS, and NPKM treatments had equal N inputs. The crop yields were measured over the whole experimental duration. Soil samples were collected from the topsoil(0–10 and 10–20 cm) and subsoil(20–40 cm) layers for assessing soil aggregates and taking SOC and TN measurements. Compared with the NPK treatment, the SOC and TN contents increased significantly in both the topsoil(24.1–44.4% for SOC and 22.8–47.7% for TN) and subsoil layers(22.0–47.9% for SOC and 19.8–41.8% for TN) for the organically amended treatments(NPKS, NPKM and 1.5NPKM) after 30 years, while no significant differences were found for the average annual crop yields over the 30 years of the experiment. The 0–10 cm layer of the NPKS treatment and the 20–40 cm layer of the NPKM treatment had significantly higher macroaggregate fraction mass proportions(19.8 and 27.0%) than the NPK treatment. However, the 0–10 and 20–40 cm layers of the 1.5NPKM treatment had significantly lower macroaggregate fraction mass proportions(–19.2 and –29.1%) than the control. The analysis showed that the higher SOC and TN in the soil of organically amended treatments compared to the NPK treatment were related to the increases in SOC and TN protected in the stable fractions(i.e., free microaggregates and microaggregates within macroaggregates), in which the contributions of the stable fractions were 81.1–91.7% of the increase in SOC and 83.3–94.0% of the increase in TN, respectively. The relationships between average C inputs and both stable SOC and TN stocks were significantly positive with R2 values of 0.74 and 0.72(P<0.01) for the whole 40 cm soil profile, which indicates the importance of N for soil C storage. The results of our study provide key evidence that long-term combined organic and chemical nitrogen fertilization, while maintaining reasonable total N inputs, benefited soil C and N storage in both the topsoil and subsoil layers.

Total N,total P and organic matters content in floodplain soils of Xianghai Nature Reserve

Soil sediment samples of 10 layers with a spacing of 10 cm each were collected in different floodplain zones adjacent to Huolin River in the Xianghai Nature Reserve, and contents of total N, total P and organic matters were analyzed. The results showed that contents of total N, total P and organic matters were generally decreasing with the increase of distance from sample locations to the river channel, and contents of the three items were generally higher in the upper soil layer than that in the lower soil layer. The content variations displayed how flooding functions influenced nutrient matter content variations in floodplain soils since the flood inundation frequencies of the sample locations varied. The correlation analysis displayed that there were remarkable relativities between total N, total P and organic matters within definite spatial distance from the Huolin River channel.

动物源有机肥料对土壤N、P、K动态变化的影响

为了了解动物源产品作为有机肥源施入土壤后的养分变化情况,分别将血粉、肉粉、骨粉按正交设计以不同比例与土壤混合后装入花盆中,于一定时期取样测定土壤速效养分,结果表明:不同的处理中土壤碱解氮、速效磷、速效钾均呈现前期上升、达到高峰然后再回落的特点,只是高峰出现的时间和峰值不同。不同的是速效钾变化幅度极小,并且最终回落到低于初始状态的水平。动物源有机肥料可以缓慢释放植物所需养分,有利于植株的生长。

盐渍土区棉花N、P、K肥效应研究

应用盆栽和田间试验对盐渍土棉花N、P、K肥效应进行了研究。结果表明 ,合理施用P、K肥能提高棉花体内过氧化物酶 (POD)活性 ,减少丙二醛 (MDA)含量 ,改善P、K营养 ,维持K+ 、Na+ 平衡 ,显著增强棉花耐盐性 ;合理增施N、P肥 ,可显著提高盐渍土棉花产量 ,有利于改善棉纤维品质 ,以N用量 1 95kg/hm2 、P2 O5用量 1 65kg/hm2(N1 95P1 6 5)

不同年龄早实核桃园土壤N·P·K含量变化研究

[目的]探明不同年龄核桃生长地不同土层N、P、K的含量和规律。[方法]取不同年龄时期早实薄皮核桃新品种绿岭园地不同土层土样,测定其中有机质和速效N、P、K含量。[结果]结果表明：在1～8年的核桃园地中,各土层土壤有机质含量呈依次下降的趋势,上层土（0～20 cm）（中层土（21～40 cm）（下层土（41～60 cm）,中层土速效N含量高于上层土和下层土;在1～4年的园地中,中层土速效P含量高于上层土和下层土,5～8年的园地中,则低于上层土和下层土;在1～6年和8年的园地中,中层土速效K含量高于上层土和下层土,7年的园地中,则低于上层土。1年园地中层土速效N和速效P含量最高,分别为76.3 mg/kg和103.21 mg/kg;5年园地中层土速效K含量最高,速效P含量最低,分别为149.0 mg/kg和6.34 mg/kg;6年园地上层土速效N含量最低,为58.5 mg/kg;7年园地下层土速效K含量最低,为58.5 mg/kg。[结论]该研究可为确定不同年龄早实核桃园土壤的科学施肥管理提供理论依据。

有机肥与化肥配施对春小麦叶片及籽粒N、P、K含量的影响

在景泰县采用全膜覆土栽培方式,田间设置有机肥和化肥配施试验,分别于春小麦生长3个关键时期(拔节期、抽穗期、成熟期)测定春小麦叶片N、P、K元素含量,收获后测定籽粒N、P、K元素含量,结果表明,有机肥和氮肥配施对小麦叶片N、P、K元素含量的影响比较明显。随着氮肥和有机肥施用量的增加,叶片和籽粒N含量增加,叶片和籽粒的P、K元素含量随着有机肥施入量增加而增加。故低量有机肥配施高量氮肥、高量有机肥配施低量氮肥均对春小麦的生长发育和产量形成具有积极意义。

生物有机肥与N、P、K复合肥在南方果树上的应用效果分析

生物有机肥与N、P、K复合肥在南方果树上都是较常使用的肥料,但具体的使用效果有什么区别呢?我们分别在香蕉、荔枝、龙眼等作物上做了等值成本的对比试验。

茭白地上部N、P、K含量及变化趋势

茭白植株地上部总体上N、K含量较高 ,P含量低。干物质中P、K含量的变化总体呈下降趋势 ,N的含量在孕茭膨大期有一个激增过程。叶片和短缩茎N、P、K的含量变化与植株N、P、K含量变化基本一致。肉质茎膨大过程中N、P、K含量均显著增加 ,叶片和短缩茎的N、P、K含量有不同程度的下降。叶片制造的养分首先送往短缩茎 ,短缩茎积累达一定程度而肉质茎尚未膨大时 ,叶片进行自身积累 ,肉质茎开始膨大后 。

Identifying the influence of urbanization on soil organic matter content and p H from soil magnetic characteristics

Soil magnetic characteristics are correlated with soil p H and organic matter content. Analyzing soil magnetic characteristics, organic matter content and p H can indirectly evaluate soil pollution caused by human activities. This study analyzed the soil magnetic characteristics, organic matter content and p H in surface soil samples from different land use types in Shihezi city, a newly and rapidly developing oasis city in Xinjiang of China. The aims of this study were to explore the possible relationships among the soil magnetic parameters and thereby improve the understanding of influence of urbanization on soil properties. Eighty surface soil samples at the depth of 0–10 cm were collected from 29 July to 4 August 2013. The results showed that the magnetic minerals in surface soil were dominated by ferromagnetic minerals. Spatially, the magnetic susceptibility（χLF）, anhysteretic remanent magnetization susceptibility（χARM）, saturation isothermal remanent magnetization（SIRM） and ＂soft＂ isothermal remanent magnetization（SOFT） were found to be most dominant in the new northern urban area B（N-B）, followed by built-up areas（U）, suburban agricultural land（F）, and then the new northern urban area A（N-A）. The values of χLF, χARM, SIRM and SOFT were higher in the areas with high intensities of human activities and around the main roads. Meanwhile, the property ＂hard＂ isothermal remanent magnetization（HIRM） followed the order of U〉N-B〉F〉N-A. Built-up areas had an average p H value of 7.93, which was much higher than that in the new northern urban areas as well as in suburban agricultural land, due to the increased urban pollutant emissions. The average value of soil organic matter content in the whole study area was 34.69 g/kg, and the values in the new northern urban areas were much higher than those in the suburban agricultural land and built-up areas. For suburban agricultural land, soil organic matter content was significantly negatively correlated with χLF, and had no correlation with other magnetic parameters, since the soil was frequently ploughed. In the new northern urban areas（N-A and N-B）, there were significant positive correlations of soil organic matter contents with χARM, SIRM, SOFT and HIRM, because natural grasslands were not frequently turned over. For the built-up areas, soil organic matter contents were significantly positively correlated with χLF, χARM, SIRM and SOFT, but not significantly correlated with frequency-dependent susceptibility（χFD, expressed as a percentage） and HIRM, because the soil was not frequently turned over or influenced by human activities. The results showed that soil magnetic characteristics are related to the soil turnover time.

大气CO_2浓度升高对稻麦根系周围土壤C、P、K的影响

利用FACE(free air carbon dioxide enrichment)技术平台,在两种氮肥施用(低氮,LN和常规氮,NN)水平下,研究CO2浓度升高对水稻和小麦收获后根际和非根际土壤可溶性碳、有机磷、速效磷和速效钾的影响。结果表明,相对于对照CO2浓度处理,高CO2浓度处理在显著增加作物生物量的前提下,土壤速效磷和速效钾不但没有降低反而增加,增加幅度小麦季大于水稻季,根际大于非根际;水稻季土壤可溶性碳含量增加,且NN水平下水稻和小麦季进入土壤的可溶性碳增加,导致土壤有机磷降低幅度低于LN水平,且水稻季根际土壤大于非根际土壤,有机磷的降低是保证有效磷升高的一个重要因素,增加氮肥施用将有利于土壤有机磷的增加,对维持土壤磷的供给有积极作用,有利于作物对高CO浓度的持续响应。

Effects of Nitrogen,Phosphorus and Potassium Application on Growth and Dry Matter Accumulation in Mulberry

In this paper, the effect of different fertilizer treatments on the main indexes of growth and development and dry matter accumulation of perennial mulberry, which is cut and pruned in summer, were studied with ‘3414’ field experiment design. The results showed that N, P, and K at proper amounts could promote mulberry growth and development, improve its dry matter content, increase its dry matter accumulation. The effects of N, P, K on leaf yield per plant were respectively expressed as follows： N2 N3 N1 N0 , P2 P1 P3 P0 , K2 K1 K3 K0 . It can be concluded that the recommended fertilizer amounts of dry matter accumulations in mulberry leaf were 694.36 kg/hm2 of N, 198.15 kg/hm2 of P, and 274.26 kg/hm2 of K and the dry matter achieved the maximum at 8 045.04 kg/hm2 . The recommended fertilizer amounts of accumulated dry matter in branch were 1 000.05 kg/hm2 of N, 242.04 kg/hm2 of P, and 218.01 kg/hm 2 of K, and the dry matter achieved the maximum at 5 969.05 kg/hm2 . The recommended fertilizer amount in young shoots were 883.76 kg/hm2 of N, 204.48 kg/hm2 of P and 426.59 kg/hm2 of K and dry matter achieved the maximum at 1 410.24 kg/hm2 . This paper could provide reference for the construction of highly-qualified mulberry field in Sichuan hilly area.

Changes in Contents of N,P,K,pH and Organic Matter of Soil Experiencing Hydro-Fluctuation in Three Gorges Reservoir

Setting monitoring transect in the middle and shallow water area(altitude 156-172 m) in Three Gorges reservoir hydro-fluctuation belt to research the changing characteristics of the contents of N, P,K,pH and organic matter of the soil which experienced the influence of fluctuation the first time. The results showed that by the influence of water level fluctuating,contents of soil N,P,K,pH and organic matter had reduced in different soil layers in hydro-fluctuation belt.The available N decreased by 41.53%-59.87%,available P decreased by 5.26%- 36.76%,available K decreased by 3.55%-45.56%, total N decreased by 9.52%-40.00%,total P had no change generally,total K had decreased a little, content of organic material decreased by 7.62%- 37.83%%,pH value turned to neutral,changed by 1.73%-9.58%.

Fertilization Affects Biomass Production of Suaeda salsa and Soil Organic Carbon Pool in East Coastal Region of China

Land use practice significantly affects soil properties. Soil is a major sink for atmospheric carbon, and soil organic carbon （SOC） is considered as an essential indicator of soil quality. The objective of this study was to assess the effects of N and P applied to Suaeda salsa on biomass production, SOC concentration, labile organic carbon （LOC） concentration, SOC pool and carbon management index （CMI） as well as the effect of the land use practice on soil quality of coastal tidal lands in east coastal region of China. The study provided relevant references for coastal exploitation, tidal land management and related study in other countries and regions. The field experiment was laid out in a randomized complete block design, consisting of four N-fertilization rates （0 （NO）, 60 （N1）, 120 （N2） and 180 kg ha-1 （N3））, three P-fertilization rates （0 （P0）, 70 （P1） and 105 kg ha-~ （P2）） and bare land without vegetation. N and P applied to S. salsa on coastal tidal lands significantly affected biomass production （above-ground biomass and roots）, bulk density （Pb）, available N and P, SOC, LOC, SOC pool and CMI. Using statistical analysis, significantly interactions in N and P were observed for biomass production and the dominant factor for S. salsa production was N in continuous 2-yr experiments. There were no significant interactions between N and P for SOC concentration, LOC concentration and SOC pool. However, significant interaction was obtained for CMI at the 0-20 cm depth and N played a dominant role in the variation of CMI. There were significant improvements for soil measured attributes and parameters, which suggested that increasing the rates of N and P significantly decreased Pb at the 0-20 cm depth and increased available N and P, SOC, LOC, SOC pool as well as CMI at both the 0-20 and 20-40 cm depth, respectively. By correlation analysis, there were significantly positive correlations between biomass （above- ground biomass and roots） and SOC as well as LOC in 2010 and 2011 across all soil depth, respectively. The treatment with N at 180 kg ha-~ and P at 105 kg ha-1 was superior to the other treatments. The results from the 2-yr continuous experiments indicated that, in short-term, there were a few accumulation of SOC and LOC concentrations by means of N and P application to S. salsa, whereas in the long run, S. salsa with N and P application was recommended for coastal tidal lands because of its great potential of carbon sequestration, improvements of soil nutrition status and promotion of soil quality.