SP5 - Methods

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Evaluation of Available Nutrition

Sampling Design

  • NorthSouth gradient approximately from Astana to Petropawl
  • different land uses and managements
  • per sampled field 1 soil profile (sampling each horizon, 1 m depth) and 6 satellites (10 cm increments, 030 cm depth)

 

Measurements

  • pH in water und calciumchloride; all samples
  • electrical conductivity; all samples
  • exchangeable bases and cation exchange capacity (CEC) und base saturation (BS): bariumchloride method (after Hendershot and Duquette, 1986); all samples
  • potassium and phosphorous: calciumacetatelactate method (after VDLUFA, 2012); all samples
  • mineralized nitrogen (ammonium, nitrate): photometrically (extraction: VDLUFA, 2002; photometrical analysis after Skalar Methods, 2006); all samples
  • trace nutrition according to Mehlich III; for selected samples

 

Evaluation

  • Calculation of stocks according to the equivalent soil mass principle (Ellert and Bettany, 1995)
  • statistical analysis will follow
     

 

Analysis of Nitrogen Availability depending on the Soil Management

Quantification of Nitrogen Availability depending on the Soil Management and Quantification of Nitrogen Uptake regarding the Application of Liquid Fertilizer Application

Experimental design

On two neighbouring fields under wheat but different soil management the fertilizers Silitra and Ammoniumsulfate were applied each in liquid and solid form whereas the pure nitrogen amount was the same. Additionally AHL was applied in liquid form. Each fertilizer species had its on stripe. On each of these stripes the fertilizers were labelled with their 15N labeld pendent, each in form of nitrate and ammonia. This labelling was conducted within one seeding furrow for 3 m. 2 mL of 15N labeld N-species were applied for liquid fertilizers, 0.5 mL for solid fertilizers, whereas the 15N enrichment was constant.

 

Sampling

Sampling was conducted three times at important dates during the vegetation period. Hereby a plant is sampled above- and below ground according to the depths of soil sampling. Soil samples (same volume) were taken around the sampled plant in different depths (up to 30 cm).

 

Measurement

The soil moisture of each sample was determined. Directly after sampling soil samples are extracted in calciumchloride and subsequently measured photmetrically for mineralized nitrogen. These extracts and the plant samples are analysed in Germany for d15N on the EA-IRMS and 15N-species on the SPINMAS.

Nitrogen Gross-Mineralisation

Experimental Design

On three different dates within the vegetation period, the gross-nitrogen-mineralization is determined according to the rooting depth of the plants. Therefore, each 0.5 mL of 15N labeld ammonia and nitrate, each in triplicates, are injected with cannulas on microplots of 1600 cm² in depths of 0-5, 5-15 and 15-30 cm. After injection of 15N labeld nitrogen species the cannulas were flushed two times with 0.5 mL water and cannulas remained in the soil for 30 minutes (retention time).

 

Sampling

One day after application of the 15N labeld nitrogen species one plant and the surrounding soil were sampled. The plant is sampled above- and belowground according to the depths of soil sampling. Soil samples (same volume) are taken around the sampled plants in two different depths. The resulting hole is filled with soil again. Three days after label application another sampling using the same scheme is conducted.

 

Measurement

The soil moisture of each sample was determined. Directly after sampling soil samples are extracted in calciumchloride and subsequently measured photmetrically for mineralized nitrogen. These extracts and the plant samples are analysed in Germany for d15N on the EA-IRMS and 15N-species on the SPINMAS.