Customer Information

Ecosystem

Recommended burial period

Agriculture

1 to 4 weeks

Grassland, forest

2 to 8 weeks

Arid

2 to 12 weeks

Wetland

1 to 4 weeks

Notes

  • Use shorter burial periods for moist, fertile soils.
  • Shorter or longer burial periods may be required, depending on objectives and soil conditions.
  • Preliminary experiments are valuable to determine optimal burial periods.
  • A consistent burial period is required to reliably compare treatment effects on soil nutrient supply due to non-linear adsorption of nutrients by PRS® probes.

 

 

 

 

 

 

 

 

 

 

 

 

 

Actual Example

Nutrient supply to PRS® probes following oats or clover determined with eight one-week burial periods vs. one eight-week burial period (Salisbury, 2000).

Preceeding crop

Burial treatment

Nutrient supply (mg/m2 of membrane/burial period)

NO3-N

NH4-N

P

K

Ca

Mg

Oats

1 wk * 8

162

8

51

177

1879

127

 

8 wk * 1

515

7

73

181

3091

183

               

8 wk:1 wk

3.2

0.9

1.4

1.0

1.6

1.4

               

Clover

1 wk * 8

252

9

42

260

1659

119

 

8 wk * 1

685

10

64

259

3108

180

               

8 wk: 1 wk

2.7

1.0

1.5

1.0

1.9

1.5

Notes

  • One- week burials were deployed sequentially (same slots).  Measurements are expressed per burial period (per one week or per eight weeks).
  • Compared to one-week burial, eight-week burial period measurements were 3-fold greater (NO3-N), 40-90% greater (P, Ca and Mg) or the same (NH4-N, K).
  • Thus, soil nutrient supply was not linear for any of these nutrients: eight-week burial measurements were not eight times higher than one-week burials.
  • Relative differences between treatments were consistent among burial treatments for all nutrients except NO3-N, which was 56% greater following clover than oat based on one-week burials, but 33% greater based on the eight-week burial.
  • Nitrogen uptake by winter wheat over eight-week period was 58% greater following clover than oat.
  • Weekly measurements for NO3-N tended to decrease with time and were most strongly affected by preceding crop during initial few weeks.
  • Eight-week measurements were similar to maximum weekly measurements for Ca, Mg and P.
  • Eight-week measurements were similar to measurements over final few weeks for NH4-N and K.

 

Considerations

  • Macro-nutrient supply rates can be determined in moist soils using burial periods of as little as one hour.
  • Most research has utilized burial periods of one to eight weeks. This period is sufficient to ensure that impacts of disturbance due to installation are minimal and provides a sensitive indicator of soil nutrient activity.
  • As nutrients are only mobile in moist soils, burial periods in dry environments should include at least one period of significant precipitation.
  • PRS® probes can also be deployed overwinter, but nutrient adsorption will only occur during periods when soils are unfrozen.
  • NO3-N increases with burial duration unless there is strong competition from plants.
    • Studies evaluating soil N mineralization in the presence of plants often install probes within root-enclosure cylinders (RECs) to prevent plant uptake.  Sequential burial in RECs for periods of one to four weeks is used to evaluate seasonal differences in soil N mineralization.
    • Without use of RECs, burial of PRS® probes for one to four weeks prior to the period of rapid plant uptake is often useful to evaluate treatment differences in soil N supply.
    • Long-term burials in the presence of plants often provide a sensitive indicator of soil N fertility, but underestimates total soil N supply to plants.
    • Burial periods should not exceed the adsorption capacity of PRS® probes: the maximum adsorption for NO3-N is 2100 mg N/m2 of membrane, but should not exceed <1000 mg N/m2.  This is only an issue in heavily fertilized soils (see interpretation).
  • Nutrients other than NO3-N are less sensitive to use of RECs or burial period.
  • Nutrients that are strongly held by PRS® probes (e.g., Ca, Mg, Fe) are stable or increase with time.  Measurements from long-term burials reflect periods of maximum nutrient activity.
  • Nutrients that are weakly held by PRS® probes are dynamic.  Measurements from long-term burials primarily reflect nutrient activity prior to retrieval.