Soil water and air Ross Monaghan Cecile de
- Slides: 36
Soil water and air Ross Monaghan & Cecile de Klein Ag. Research, Invermay
Overview n n Balancing water and air in soils Problems arising from too much water Methods of measuring soil water content Management practices for regulating soil water: air ratio
1. Balanced soil… Solids Pores
The balancing act…. n Too much water n n Anaerobic Loss of nutrients Greater susceptibility to structural damage Too much air n Drought
Soil water and air for plant growth Water for photosynthesis: CO 2 + H 2 O + energy → carbohydrate H 2 O Air (oxygen) for root respiration: Carbohydrate + O 2 → CO 2 + H 2 O + energy O 2 H 2 O
Soil pores n Large pores (macro or transmission) ð ð n Storage pores ð ð n Greater than 50 m dia. Drain under gravity 0. 5 to 50 m dia. Hold plant available water Residual pores (micro pores) ð ð Less than 0. 5 m dia. Hold unavailable water
Soil pores root Soil particle
Stages of soil water status n Saturated soil ð n Field capacity ð n All pores are filled with water Storage and residual pores are filled with water Wilting point ð Only residual pores are filled with water
The bucket model of soil water… Rain Evaporation Saturation Field capacity Water holding capacity Soil water deficit Permanent wilting point Drainage
Soil water Field capacity Permanent Saturated wilting point root Soil particle
ET slows as soil dries Relative evapotranspiration 1 0. 5
Soil water tension (log cm H 2 O or p. F) p. F curves Permanent wilting point Field capacity
Water holding capacities of topsoil n 16. 3 mm water/100 mm soil depth Silt loam 22. 5 n Sand n Clay 13. 6
2. Problems with too much water n Nutrient losses n n Drainage Overland flow n Compaction/pugging n Greenhouse gas emissions
Rainfall v ET Monthly rainfall and ET (mm)
Fate of surplus rainfall
Nutrient losses n Drainage n n Nitrate leaching Overland flow n Phosphorus and ammonia losses
Soil compaction/pugging
Unaffected by compaction Depth (cm) 0 10 Slightly affected Moderately affected Severely affected
Soil compaction → Reduces % of macro pores → Reduces soil drainage and aeration → Reduces plant growth Pugging cycle
Greenhouse gas emissions in New Zealand Nitrous oxide 14% Carbon dioxide 40% Methane 44%
Greenhouse gas emissions from soil n Nitrous oxide (laughing gas) N 2 O n Biological denitrification (NO 3 - → N 2 O) n Anaerobic process n High water filled pore space, i. e. low air filled pore space
Effect of soil water content N 2 O emission (kg N/ha. day)
3. Methods for measuring soil water n Gravimetric n TDR n Aquaflex n Neutron probes n Remote sensing
Aquaflex
4. Management practices Rain (or irrigation) Evaporation - mulching Water holding capacity -Avoid compaction -Maintain good structure Provide good drainage
Minimize heavy traffic Good drainage Back-fencing Feed-pads
Tools & info for farmers n n n Commercial test for soil compaction on-farm E Lab Ltd Best practices
Field drainage Fissure network Trench spoil 25 cm Pea gravel 45 cm Mole channel Intercepting tile line
Maintaining good soil structure Stable aggregates (%)
- Water and water and water water
- Bandura ross and ross 1961 evaluation
- Environment vs ecology
- Nuala barry monaghan
- Tom monaghan brother
- Chris monaghan photography
- Elaine monaghan
- Yvonne monaghan
- Cécile crespy
- Haitian
- Cecile duvelle
- Camille claudel louise athanaïse cécile cerveaux
- Cecile barbier
- Neuropsychologue senlis
- Cecile chanoz
- Cecile duvelle
- Marie cécile escande varniol
- European psychiatry
- Cecile betermin
- Air higroskopis air kapiler dan air gravitasi
- Living soil vs dead soil
- Convergent plate boundaries
- Soil and water relationship
- Principles of soil and water conservation
- Agronomic measures of soil and water conservation
- Texas state soil and water conservation board
- Food air and clothes
- Sap flow
- Importance of soil
- Water retention in soil
- Available water definition
- Water content of soil
- Soil texture water holding capacity
- An ecosystem in which water either covers the soil
- Explain how water erosion by groundwater can form a cave.
- Saturated flow of water in soil
- Single acting cylinder pneumatic circuit