This manual is a compilation of methods used for soil and plant analysis at the Analytical Services Laboratory of the Northern Forestry Centre (NoFC) of Forestry Canada's Northwest Region. The intent of this manual is not so much to recom­ mend certain procedures over others, but to indicate methods used in our labora­ tory, why these methods are used, their expected precision and accuracy, and their strengths and weaknesses. RESUME Sont reunies dans Ie present guide les methodes utilisees pour l'analyse des plantes et des sols au Laboratoire des services d' analyse du Centre de foresterie du Nord de Forets Canada (region du Nord-Ouest). L' objectif de ce guide n' est pas tant de recommander certaines methodes de preference a d'autres, mais d'indiquer celles qui sont utilisees dans notre laboratorre, la raison de leur utilisation, I' exact­ itude et la precision que I' on peut attendre de leurs resultats, leurs points forts et leurs points faibles. /nf. Rep. NOR-X-3/9 iii iv In! Rep. NOR-X-319

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Methods manual for forest soil and plant analysis

A new soil test was developed for simultaneous extraction of NO3, P, K, Zn, Fe, Cu and Mn from alkaline soils. The new extraction solution is 1 M in ammonium bicarbonate (NH4HCO3), 0.005 M in Diethylene Triamine Pentaacetic Acid (DTPA) and has a pH of 7.6. The new extracting solution should be stored under mineral oil. Ten grams of soil are weighed out into 125 ml Erlenmeyer flasks. Two 2.5 ml scoops of Fisher G carbon black (to remove color for colorimetric determination of nitrates) are added to each soil, followed by 20 ml extracting solution. The soil mixture is then shaken on an Eberbach reciprocal shaker for 15 minutes at 180 cycles per minute. The extract is then filtered through a Whatman 42 filter paper or its equivalent for NO3, P, K, Zn, Fe, Cu and Mn determinations. The results obtained with the new procedure are highly correlated with results obtained with Olsen's P test, ammonium acetate K test, and Lindsay and Norvell's DTPA‐Zn, Fe, Cu and Mn test. Regression equations between the ...

A new soil test for simultaneous extraction of macro‐ and micro‐nutrients in alkaline soils

The controls of potential nitrogen mineralization, nitrate production, and nitrate mo- bilization in a wide range of forest ecosystems were investigated through a combination of field and laboratory experiments. Trenched plot experiments were performed in 17 forests, and laboratory incubation studies of potential ammonium and nitrate production were made on soils from 14 of these sites. The site with the greatest potential for nitrate production in the laboratory was a New Hampshire northern hardwoods forest. Several other sites, including New Hampshire balsam fir, Indiana maple- beech, New Mexico aspen, and Oregon western hemlock forests, also had high potential nitrate production. All of these sites also had rapid nitrate movement to below the rooting zone following trenching in the field. Of nine processes which could be important in preventing or delaying solution losses of nitrate from disturbed forests, two appeared most important among the forests we examined. Low net nitrogen mineralization (caused by either nitrogen immobilization or low gross nitrogen mineralization) and lags in nitrification (probably caused by either low initial populations of nitrifying bacteria or the allelochemic inhibition of nitrification) were identified as important in several sites and in different regions. A direct relationship between the amount of nitrogen in annual litterfall and the proportion of forest floor nitrogen mineralized in laboratory incubations was observed, suggesting that refractory organic nitrogen compounds are produced in nitrogen-poor sites. An inverse relationship was found between the amount of nitrogen in litterfall in these and other sites and the carbon:nitrogen ratio of that litterfall, suggesting that the immobilization capacity of litter is increased in nitrogen-poor sites. The presence and length of lags in nitrification were inversely correlated with the mean concentration of mineral nitrogen in mineral soil. These patterns suggest that nitrogen retention within disturbed forest ecosystems can be caused by low nitrogen availability prior to disturbance.

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A Comparative Analysis of Potential Nitrification and Nitrate Mobility in Forest Ecosystems

Nitrate and Exchangeable Ammonium Nitrogen

Soil aggregation in relation to other soil properties was studied along a climatological transect in the Southeast of Spain. Three sites were selected along this transect ranging from semiarid to subhumid climatological conditions. The aggregate size distribution, the macro and microaggregate stability of the superficial soil horizon and their relations with other soil properties were analysed. Large aggregates (>10, 10–5, 5–2 mm) were present in highest proportions in the most arid of the studied areas. These large aggregates were associated with high values of water-stable microaggregates; however, they did not improve soil structure and are related to high bulk densities and low water retention. Aggregates 1–0.105 mm were positively correlated to medium, fine, very fine sand and silt fractions and to organic matter. Aggregates Water stability of microaggregates showed a positive correlation with clay content while the stability of the macroaggregates depended on the organic matter content when the organic matter content was greater than 5 or 6%. Below that threshold the carbonate content was strongly correlated with aggregate stability. A general conceptual scheme of associations between aggregate size distribution, water-stable microaggregation and textural characteristics for the area was developed. The land use history affecting soil overlaps the pattern of climatological situations and has to be taken into account. Aggregate size distribution and stability can be used as indicator of soil degradation, but not as a unique parameter.

Rathje

Papers

Jackson, M. L.: Soil chemical analysis. Verlag: Prentice Hall, Inc., Englewood Cliffs, NJ. 1958, 498 S. DM 39.40