Foliar potassium status explains douglas fir response to nitrogen fertilization in the Inland Northwest,USA

Despite apparently inadequate N levels throughout the Inland Northwest of the United States, trees on some sites showed no increased growth 6 yr after N fertilization. Nor did higher N application rates consistently produce higher response. These facts indicated that other factors are limiting tree growth at these sites. Results suggest that K status is one important factor, influencing N fertilization response in the following general ways: (1) for stands with low pretreatment foliar K levels, the amount and duration of growth response are reduced, and higher N fertilizer rates produce less response; and (2) for all stands, growth response declines when foliar K decreases after N fertilization.     

Predicting nitrogen fertilizer response in unthinned stands of Douglas‐fir

Abstract

The mineralization potential of forest soils is a useful tool in predicting nitrogen fertilizer response in unthinned stands of Douglas‐fir. As the mineralization potential of the soil increased, diameter growth for 200 lbs/A of added N decreased. Significant growth response could not be detected when mineralizable nitrogen level was above 46 ppm.

Percent stocking is also an important variable in predicting diameter growth response in these stands. For a given nitrogen level, response decreased with increasing stocking.

When stocking and mineralizable nitrogen are used together, they account for a significant portion (86%) of the variation in growth response.     

Inherent differences in response of Douglas fir families to nitrogen and phosphorus supply levels

Douglas fir (Pseudotsuga menziessi [Mirb.] Franco) seedlings from a half diallel mating design showed significant family by nutrient interactions when grown in a 3N × 3P × 15 family factorial experiment for 2 yr. Differences in response of these families to N and P treatment levels were related to nutrient productivity (dry matter production nutrient^–1 time^–1 ), but unrelated to the proportion of dry matter allocated to root growth, or to nutrient net uptake rate. Significance of general combining ability for N and K productivity showed clonal control of these characters. Evidence for genetic control of tissue N% and K%, shoot:root ratio. and N uptake rate were also shown.     

土壤碳氮对多年生能源草、覆盖作物和氮施肥的响应

Cover crop and nitrogen(N) fertilization may maintain soil organic matter under bioenergy perennial grass where removal of aboveground biomass for feedstock to produce cellulosic ethanol can reduce soil quality. We evaluated the effects of cover crops and N fertilization rates on soil organic carbon(C)(SOC), total N(STN), ammonium N(NH_4-N), and nitrate N(NO_3-N) contents at the0–5, 5–15, and 15–30 cm depths under perennial bioenergy grass from 2010 to 2014 in the southeastern USA. Treatments included unbalanced combinations of perennial bioenergy grass, energy cane(Saccharum spontaneum L.) or elephant grass(Pennisetum purpureum Schumach.), cover crop, crimson clover(Trifolium incarnatum L.), and N fertilization rates(0, 100, and 200 kg N ha~(-1)). Cover crop biomass and C and N contents were greater in the treatment of energy cane with cover crop and 100 kg N ha~(-1) than in the treatment of energy cane and elephant grass. The SOC and STN contents at 0–5 and 5–15 cm were 9%–20% greater in the treatments of elephant grass with cover crop and with or without 100 kg N ha~(-1)than in most of the other treatments. The soil NO_3-N content at 0–5 cm was 31%–45% greater in the treatment of energy cane with cover crop and 100 kg N ha~(-1)than in most of the other treatments.The SOC sequestration increased from 0.1 to 1.0 Mg C ha~(-1)year~(-1)and the STN sequestration from 0.03 to 0.11 Mg N ha~(-1)year~(-1)from 2010 to 2014 for various treatments and depths. In contrast, the soil NH_4-N and NO_3-N contents varied among treatments,depths, and years. Soil C and N storages can be enriched and residual NO_3-N content can be reduced by using elephant grass with cover crop and with or without N fertilization at a moderate rate.     

Bacterial and fungal contributions to soil nitrogen cycling under Douglas fir and red alder at two sites in Oregon

A study was conducted at two experimental tree plantations in the Pacific Northwest to assess the roles of bacteria and fungi in nitrogen (N) cycling. Soils from red alder (Alnus rubra) and Douglas-fir (Pseudotsuga menziesii) plots in low- (H.J. Andrews) and high- (Cascade Head) productivity stands were sampled in 2005 and 2006. Fungal:bacterial ratios were determined using phospholipid fatty acid (PLFA) profiles and quantitative (Q)-PCR. Ratios from these two molecular methods were highly correlated and showed that microbial biomass varied significantly between the two experimental sites and to a lesser extent between tree types with fungal:bacterial biomass ratios lower in more N-rich plots. ¹⁵N isotope dilution experiments, with ammonium (NH₄⁺) and nitrate (NO₃^?), were paired with antibiotics that blocked bacterial (bronopol) and fungal (cycloheximide) protein synthesis. This modified isotope dilution technique was used to determine the relative contribution of bacteria and fungi to net N mineralization and gross rates of ammonification and nitrification. When bacterial protein synthesis was blocked NH₄⁺ consumption and nitrification rates decreased in all treatments except for NH₄⁺ consumption in the Douglas-fir plots at H.J. Andrews, suggesting that prokaryotic nitrifiers are a major sink for mineral NH₄⁺ in forest soils with higher N availability. Cycloheximide consistently increased NH₄⁺ consumption, however the trend was not statistically significant. Both antibiotics additions also significantly increased gross ammonification, which may have been due to continued activity of extra- and intracellular enzymes involved in producing NH₄⁺ combined with the inhibition of NH₄⁺ assimilation into proteins. The implication of this result is that microorganisms are likely a major sink for soil dissolved organic N (DON) in soils.     

The influence of weather variation on regional growth of Douglas fir stands in the U.S. Pacific Northwest

In this paper we examine the influence of precipitation and temperature deviations on regional volume growth rates in even-aged, unmanaged second-growth Douglas fir (Pseudotsuga menziesii [Mirb.] Franco) stands. Between 1969 and 1986, average volume growth rates in natural stands of coast Douglas fir in western Washington and Oregon were negatively correlated with high summer temperatures and positively correlated with higher temperatures during the non-growing season. Results support the hypothesis that cool wet summers and mild winters contribute to high productivity of conifers in the Pacific Northwest.     

Inherent differences in response of douglas fir families to nitrogen and phosphorus supply levels

Douglas fir (Pseudotsuga menziessi [Mirb.] Franco) seedlings from a half diallel mating design showed significant family by nutrient interactions when grown in a 3N × 3P × 15 family factorial experiment for 2 yr. Differences in response of these families to N and P treatment levels were related to nutrient productivity (dry matter production nutrient⁻¹ time⁻¹), but unrelated to the proportion of dry matter allocated to root growth, or to nutrient net uptake rate. Significance of general combining ability for N and K productivity showed clonal control of these characters. Evidence for genetic control of tissue N% and K%, shoot:root ratio and N uptake rate were also shown.     

桔梗氮、磷、钾施肥效应与施肥模式研究

采用氮、磷、钾三因素2次D-饱和最优设计(310),通过大田试验建立了氮、磷、钾施肥量与桔梗产量和总皂苷含量的效应函数。结果表明,氮、磷、钾肥对桔梗产量的影响大小依次为氮肥 钾肥 磷肥;氮、磷、钾肥对桔梗总皂苷含量的影响大小依次为氮肥 磷肥 钾肥。对各效应函数进行频率分析法寻优结果表明,桔梗目标产量在4200～4800 kg/hm2,95%置信区间的优化施肥量为N 83.72～119.41 kg/hm2、P2O5 64.10～134.39 kg/hm2、K2O 78.80～147.20 kg/hm2;桔梗总皂苷含量在5.5%以上,95%置信区间的优化施肥量为N 113.37～140.12 kg/hm2、P2O5 85.96～153.44 kg/hm2、K2O 76.86～136.38 kg/hm2;桔梗高产优质高效栽培最优施肥量为N 113.37～119.41 kg/hm2、P2O5 85.96～134.39 kg/hm2、K2O 78.80～136.38 kg/hm2,N、P2O5、K2O的最优施用量配比为1︰0.72～1.18︰0.66～1.20。     

Bacterial and fungal response to nitrogen fertilization in three coniferous forest soils

Forest soil carbon (C) pools may act as sinks for, or sources of, atmospheric carbon dioxide, while nitrogen (N) fertilization may affect the net exchange of C in forest ecosystems. Since all major C and N processes in soil are driven by soil microorganisms, we evaluated the effects of N fertilization on biomass and bacterial and fungal activity in soils from three Norway spruce forests with different climatic and N availability conditions. N deposition and net N mineralization were higher at the sites in southern Sweden than at the site in northern Sweden. We also studied the extent to which N fertilization altered the nutrient(s) limiting bacterial growth in soil. We found that on average microbial biomass was reduced by ～40% and microbial activity by ～30% in fertilized plots. Bacterial growth rates were more negatively affected by fertilization than fungal growth rates, while fungal biomass (estimated using the phospholipid fatty acid (PLFA) 18:2ω6,9) decreased more than bacterial biomass as a consequence of fertilization. The microbial community structure (indicated by the PLFA pattern) was changed by fertilization, but not in the same way at the three sites. Soil bacteria were limited by a lack of carbon in all forests, with the carbon limitation becoming more evident in fertilized plots, especially in the forests that had previously been the most N-limited ones. This study thus showed that the effects of N fertilization differed depending on the conditions at the site prior to fertilization.     

生土条件下冬小麦对氮、磷、钾的原始响应

配方施肥是提高作物肥料利用率和产量品质的重要措施。但氮、磷、钾营养元素之间的相互关系仍然存在一些不确定性,不同土壤肥力及不同的研究方法是造成这一结果的原因。本研究采用肥力极低的生土为基质,探讨了氮、磷、钾、有机肥及不同组合、配比对冬小麦产量和品质性状的影响。结果表明,只有磷素存在才能使小麦正常生长发育,单施氮、钾以及氮钾配施都不能保证小麦生长的基础代谢,不能形成正常产量。磷对氮的效应远大于氮对磷的效应。在土壤营养极度匮乏的非耕作土壤条件下,磷素是产量与品质形成的第一限制因素,可能作为土壤肥力形成的原始起动因素。     

9个水稻品种对氮、磷和钾肥的响应及差异

采用田间试验研究了施肥对9个水稻品种的产量、养分吸收及氮肥利用率的影响,并比较了不同品种水稻对肥料的响应差异,以期为水稻的科学施肥提供依据。结果表明,不施肥处理(CK)9个水稻品种产量变幅为5 312~7 473 kg/hm2,平均为6 444 kg/hm2,变异系数为13.3%。NPK处理显著提高了各品种产量,与CK相比,增产量分别为3 240~5 578 kg/hm2,平均增产量4 262 kg/hm2;增产率分别为47.2%~91.3%,平均增产率66.1%。试验条件下,施氮可显著提高各品种产量和氮素吸收量,与不施氮处理(PK)相比增产39.6%~90.9%,氮素吸收量增加59.4%~157.8%;磷、钾肥对水稻的产量无显著影响。不同水稻品种的氮肥利用率也存在较大差异,变幅为23.2%~53.8%。     

长期定位施肥对非石灰性潮土钾素状况的影响

利用22年肥料长期定位试验,研究施肥对土壤钾素状况的影响。结果表明,1978年到2000年,土壤钾素收支平衡的状况为:氮钾肥处理钾盈余57.72kg/hm2,氮磷钾肥处理钾亏缺192.90kg/hm2。以氮钾肥处理提高土壤中水溶性钾、非特殊吸附钾、特殊吸附钾、矿物钾最多,依次分别比对照提高5.49倍、1.13倍、2.47倍和1.11倍。氮磷钾肥和氮钾肥处理在土壤中积累各形态钾总量分别占施钾量的19.18%、20.01%。氮钾处理和氮磷钾处理土壤速效钾和土壤缓效钾含量高,在土壤剖面中分布以0—20cm含量高,20cm以下逐层降低。用X-射线衍射测定长期施钾和不施钾的土壤粘土矿物组成为:氮磷钾处理土壤粘土矿物中蒙脱石峰值高;而氮磷处理土壤粘土矿物中蛭石峰值高。     

DRIS diagnoses of soybean nitrogen,phosphorus, and potassium status are unsatisfactory

Previous research has shown that the Diagnosis and Recommendation Integrated System (DRIS) is useful to identify the nutrient most likely to limit yield of soybean (Glycine max). However, recent work with other crops has shown that DRIS diagnoses are sometimes unsatisfactory due to large numbers of false positve (F+) diagnoses, which would lead to recommendation of unnecessary fertilizer application. This paper reports a reconsideration using the prescient diagnostic analysis approach of data previously used to establish the diagnostic utility of DRIS for soybean. In addition to previously‐published evaluation criteria, the approach is extended by defining an efficiency rating which accounts for differences in the incidence of sufficient and deficient cases. Using this evaluation approach, DRIS phosphorus (P) and potassium (K) diagnoses of soybean using numerous sources of norms and methods to calculate function values and nutrient indices led to unacceptable efficiency ratings (<67%), even though accuracies often exceeded 90%. In one test, diagnoses of nitrogen (N), P, and K by both DRIS and sufficiency ranges were low in accuracy and efficiency ratings. In several other tests, poor ratings for P diagnoses often followed from low accuracy among deficient cases; i.e. false negative (F‐) diagnoses were excessive. In contrast, K diagnoses were often poor due to low accuracy among cases of sufficiency: false positive (F+) diagnoses were excessive. Despite much modification, DRIS diagnoses of soybean N, P, and K status among data sets of known response to fertilizer application are not sufficiently reliable to support routine adoption of DRIS for diagnosis.     

Amino acid composition of ryegrass in relation to nitrogen fertilization and soil water status

In a lysimeter experiment the overall amino acid concentration in dry matter of ryegrass (Lolium perenne) increased in response to nitrogen application. Lack of water reduced the overall concentration of most amino acids in dry matter except proline the concentration of which was increased. Nitrogen application as well as lack of water significantly affected the overall amino acid composition, and in particular the relative concentration of glutamic acid and proline, respectively, which might be attributed to variations in the free amino acid composition, and resulting in a decreasing overall ratio essential/not essential amino acids.     

不同土壤肥力水平下元白菜施氮、磷、钾和锌的效应

对不同土壤肥力水平下元白菜施氮、磷、钾和锌肥的效应研究表明，不同土壤肥力水平下，元白菜施氮、磷、钾和锌均能显著增加产量，分别增产12．0％～35．8％（平均24．5％）、5．3％-14．1％（平均9．7％）、11．2％．15．3％（平均12．9％）和7．5％～11．3％（平均9．1％）。在较高、中等和较低土壤肥力水平下，元白菜经济最佳施氮（N）量分别为310．5、326．1～336．6和378．9kg／hm^2，适宜磷（P2O5）用量依次为60、60-90和90～120kg/hm^2。不同土壤肥力水平地块元白菜适宜施氮时，氮肥（N）利用率在15％～20％，适宜施磷时磷肥（P2O5）利用率在9．3％～11．0％；元白菜上钾肥利用率随土壤钾素水平的降低而呈增加的趋势，不同土壤肥力地块元白菜施K2O120kg／hm^2时钾肥（K2O）利用率平均为20．4％。     

不同土壤肥力水平下元白菜施氮、磷、钾和锌的效应

对不同土壤肥力水平下元白菜施氮、磷、钾和锌肥的效应研究表明,不同土壤肥力水平下,元白菜施氮、磷、钾和锌均能显著增加产量,分别增产12.0%~35.8%(平均24.5%)、5.3%~14.1%(平均9.7%)、11.2%~15.3%(平均12.9%)和7.5%~11.3%(平均9.1%)。在较高、中等和较低土壤肥力水平下,元白菜经济最佳施氮(N)量分别为310.5、326.1~336.6和378.9 kg/hm2,适宜磷(P2O5)用量依次为60、60~90和90~120 kg/hm2。不同土壤肥力水平地块元白菜适宜施氮时,氮肥(N)利用率在15%~20%,适宜施磷时磷肥(P2O5)利用率在9.3%~11.0%;元白菜上钾肥利用率随土壤钾素水平的降低而呈增加的趋势,不同土壤肥力地块元白菜施K2O 120 kg/hm2时钾肥(K2O)利用率平均为20.4%。     

轻度盐胁迫下施氮量对小麦苗期的生理响应

通过研究轻度盐胁迫条件下,施氮量对不同品种小麦幼苗的生理响应,来筛选盐碱地上适宜的耐盐和氮素高效利用小麦品种,为黄河三角洲盐碱地的综合应用与开发提供支撑。以山东省东营市利津县渤海粮仓实验示范区的滨海轻度盐碱土为供试土壤,采用土壤培养方法,选择4个当地主流小麦品种,设置不同的氮肥用量水平(0、0.1、0.2和0.3 g/kg),研究不同小麦品种对盐碱土的响应,揭示氮肥用量对小麦氮素吸收利用和氮素代谢酶活性及其渗透调节物质的影响。结果表明在轻度盐胁迫下,随着氮肥施用量的增加,小麦的株高、干物质重、氮、钾、钠的累积量均呈增加趋势,在T3处理时最佳;与CK相比,T3处理时小麦的干物质重、氮、磷、钾、钠的累积量分别增加了87.64%、149.11%、84.51%、117.78%、39.60%;而叶片硝酸还原酶活性、可溶性蛋白含量和氮、钾含量都呈先增加后降低的趋势,在T2处理时最佳,与CK相比,分别增加了122.40%、74.54%、37.33%、22.15%。供试品种中,山农28号的小麦株高、干物质重、氮、钾、钠的累积量对氮肥施用量的响应最大,且施氮量为0.2 g/kg时小麦叶片硝酸还原酶活性、可溶性蛋白含量和氮、钾含量均达到最大值。综上所述,轻度盐胁迫条件下,4个小麦品种对氮素利用存在显著差异,山农28号小麦表现出较高的氮素利用效率和较高的盐胁迫适应性,在高氮(0.3 g/kg)时小麦的生长量、氮、钾、钠的累积量最佳,在中氮(0.2 g/kg)时硝酸还原酶活性、可溶性蛋白含量和氮、钾含量最佳。     

冬小麦-夏玉米适宜氮磷用量和平衡施肥效应

在河北衡水对冬小麦-夏玉米适宜氮、磷用量及高产高效平衡施肥效应的研究表明,在土壤中等肥力水平下,冬小麦-夏玉米施用氮肥和磷肥均能显著增加产量和效益,冬小麦和夏玉米施用氮肥分别增产11.1%～32.2%(平均22.5%)和12.5%～24.1%(平均19.2%),分别增收853.50～2 775.00元/hm2(平均1 876.60元/hm2)和1 352.33～2 293.77元/hm2(平均1 651.04元/hm2);施用磷肥分别增产8.1%～14.0%(平均11.7%)和2.5%～13.2%(平均9.1%),分别增收563.4～1 380.6元/hm2(平均974.7元/hm2)和189.74～1 458.39元/hm2(平均765.31元/hm2).冬小麦-夏玉米适宜N用量范围分别为220～260 kg/hm2和220～280kg/hm2,适宜施氮水平的氮肥利用率分别为36.5%和26.3%;适宜P2O5用量分别为90～110 kg/hm2和95～115kg/hm2,适宜施磷水平的磷肥利用率分别为16.8%～17.3%和11.8%～20.5%.冬小麦-夏玉米高产高效平衡施肥较农民习惯施肥增产5.3%～9.0%,增收454.19～992.5元/hm2,提高氮肥利用率5.0～15.2个百分点.     

Dryland corn response to tillage and nitrogen fertilization. II. P,K, CA,MG

Abstract

Nitrogen fertilization and tillage practices may influence the availability and uptake of essential plant nutrients other than N. This study was conducted to assess the interactive effects of N rate and timing and tillage practices on uptake and concentration of P, K, Ca and Mg in corn grown under dryland conditions. Potassium accumulations in no till (NT) soils were greater than in conventional till (CT) near the surface and lower than CT in the subsoil. Phosphorus and Ca levels decreased with soil depth, while Mg tended to accumulate in the subsoil. Phosphorus uptake and concentration of 5‐leaf stage corn was increased as tillage intensity decreased. Nitrogen rate at planting increased 5‐leaf P uptake but reduced P concentration; however, by silking no effect of tillage or N fertilization practice on ear leaf P concentration was obtained. Increases in 5‐leaf corn K uptake and concentration as tillage intensity decreased may have reduced Mg and Ca concentrations via cation antagonism. Ear leaf Mg and Ca concentrations were increased by N rate, probably as a result of solubilization of Ca and Mg and improved crop growth. Distribution of essential elements in the soil due to tillage in combination with varying N fertilization practices can influence temporal nutrient uptake, thereby altering plant nutrient diagnosis.     

Formula fertilization of nitrogen and potassium fertilizers reduces cadmium accumulation in Panax notoginseng

ABSTRACT

This study investigated the effect of nitrogen (N) and potassium (K) formula fertilization on cadmium (Cd) accumulation in P. notoginseng. Field investigations as well as formulated N and K fertilizers application experiments were conducted. Field investigations showed that Cd accumulation decreased PNS content in the main roots of P. notoginseng, while PNS content was promoted by soil available potassium (AK) and K in the main roots. The Cd content in P. notoginseng and the bioavailable Cd content in the soil decreased with the increasing of total K (TK) and AK in the soil. The increase of soil pH, total organic matter (TOM) and cation exchange capacity (CEC) values can reduce the bioavailable Cd content in soil, thus reducing the Cd accumulation in P. notoginseng. Under current fertilization in P. notoginseng cultivation, decreased N fertilization can alleviate the deterioration of soil physical and chemical properties. Under identical N fertilization, increasing K fertilization promoted the PNS accumulation (0.3–38.3%), also improved soil physical and chemical properties. Formulated N and K fertilizers application (1:2) experiments showed that reducing application of N and increasing K fertilization could reduce the bioavailable Cd content in soil, and the Cd content also decreased by 0.5–69.6% in P. notoginseng.

Abbreviation: PNS: P. notoginseng saponins; F(EXC): Exchangeable fraction; F(Carb): Bound to carbonates fraction; F(Fe-MnOX): Bound to iron and manganese oxides fraction; F(OM): Bound to organic matter fraction; F(RES): Residual fraction; AK: Available potassium; TK: Total potassium; CEC: Cation exchange capacity; TOM: Total organic matter