Effect of Agro-Reclamation Practices on Barley Productivity on Shallow Peat Soils (1981)

The fundamental factors dictating natural fertility disparities in peat soils with varying depths of organic deposit are nitrogen and water storage. This long-term stationary investigation assesses the viability of leveling fertility differences between shallow peat deposits (20–40 cm vs. 40–60 cm depth) via coordinated moisture management, sprinkler irrigation, mineral nitrogen fertilization, and surface sand mulching.

1. Soil Stationary Setup and Agro-Reclamation Treatments

From 1974 to 1979, the Polesian Experimental Peatland Station (Brest region) conducted field trials evaluating the efficiency of agro-reclamation techniques on spring barley (Alza cultivar) under varied nitrogen fertilization, irrigation, and mineral soil surface dressing (sand mulching).

The soil developed on wood-sedge peat (35% decomposition) underlain by fine quartz sand. The plow horizon contained 2.45% N, 0.46% P₂O₅, and 0.13% K₂O on a dry weight basis, with 14% ash content. Trials were performed concurrently across two adjacent tracts:

• Shallow peat depth: 20–40 cm;
• Moderate peat depth: 40–60 cm.

Mineral quartz sand was applied as a 2 cm surface layer (350 t/ha) prior to spring cultivation. Ammonium nitrate was applied in spring. Sprinkler irrigation was applied during stem elongation (two 50 mm waterings).

2. Meteorological Conditions and Groundwater Table Dynamics

Climatic conditions fluctuated markedly: 1974, 1975, and 1977 experienced erratic precipitation; 1976 and 1979 were severely arid, whereas 1978 experienced excessive rainfall (Table 1).

Groundwater tables on the 40–60 cm peat sector dropped to 102–116 cm during arid months, creating severe moisture deficits in the root zone (Table 2).

3. Plow Layer Moisture Dynamics and Plant Water Status

Crop water status metrics (transpiration intensity E, relative transpiration E/E₀, and cell sap concentration CSC) recorded significant physiological improvements from sprinkler irrigation and sand covering (Table 3).

In the drought of 1976, combining irrigation with sanding boosted transpiration from 0.68 to 1.17 g/g · hr, doubling relative transpiration and preventing cell sap concentration increases.

4. Impact of Sand Covering on Microclimate, Nitrification, and Nitrogen Balance

Applying a 2 cm sand mulching layer (350 t/ha) reduced surface physical evaporation and increased plow-layer moisture storage by 11–58% (Table 4).

Crucially, laboratory and lysimeter investigations revealed a dual response: moderate sand rates (up to 650–850 t/ha) invigorate nitrification by optimizing moisture; however, high rates (>5–7 cm thickness, exceeding 1200 t/ha) drop subsoil temperatures and decrease aeration, effectively conserving organic matter and reducing nitrate production to 26–63 mg NO₃ per 100 g dry peat.

5. Barley Productivity Under Contrasting Peat Depths

Four-year grain yield data on 40–60 cm peat depth (Table 5) and shallow 20–40 cm peat (Table 6) demonstrated clear operational divergences.

On soils exceeding 40 cm in peat depth, sanding and irrigation produced no statistically significant yield increments. Conversely, on shallow peatlands (20–40 cm depth), the effects were substantial (Table 6):

6. Scientific Conclusions and Practical Recommendations

1. Depth-dependent reclamation strategy: On peatlands deeper than 40 cm with seasonal groundwater tables between 86 and 104 cm, supplemental mineral nitrogen, sprinkler irrigation, and sand mulching provided no significant yield benefits in barley.
2. High return on shallow peats: On shallow peat soils (20–40 cm depth), techniques that stabilize moisture and nitrogen availability (sand mulching at 350 t/ha and irrigation) yielded marked grain gains: sanding delivered +8.2 c/ha, irrigation +2.8 c/ha, and their combination +9.5 c/ha.
3. Organic matter conservation mechanism: Surface sanding at moderate doses (650–850 t/ha) stimulates nitrification via moisture retention, while higher doses (>1200 t/ha) curb organic decomposition, establishing an effective engineering tool to decelerate peat subsidence in Polesia.

7. Original Article in Belarusian

8. References

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