Drainage the key factors and starting to address them Dick Godwin - PDF document

Dick Godwin - Drainage the key factors and starting to address them Repairing the Damaged Soils of 2012 Drainage – the key factors and starting to address them Dick Godwin Visiting Professor - Harper Adams University Outline Fundamentals The problem and the penalties Soil and water relationships Actions Short term Medium term Long term Concluding remarks www.soilandwater.org.uk

Dick Godwin - Drainage the key factors and starting to address them Effect of winter waterlogging on Winter wheat yield Sandy loam 1976-7 Source: Belford (1981), J. Agric. Sci, 97 Waterlogging Grain Straw Straw Fertile Grains/ 1000 grain treatment Yield Yield length shoots ear weight (g) (g/m²) (g/m 2 ) (cm) /m² Free draining 937 942 73 541 34.3 50.7 From 19 Nov for 837* 879*** 70 485 34.5 50.4 25 days Water table @ 5 cm From 19 Nov for 850* 827*** 69 535 32.8 48.9* 25 days Surface water table From 19 Nov for 876 847*** 75 446* 40.1 49.3 120 days Surface water table LSD (5%) 85 4 62 6.6 1.5 10.7% reduction 12.2% reduction 3.6 % reduction Effect of waterlogging on Winter wheat yield Sandy loam 1977-8 Source: Belford (1981), J. Agric. Sci, 97 Waterlogging Grain Yield Straw yield Ears/m² Grains/ear 1000 grain treatment (g/m²) (g/m²) weight (g) 1. Free draining 1281 861 517 46.6 53.7 2. From 1 Nov 1195 875 533 43.4 52.3 for 42 days 3. From 25 Jan 1235 857 477 48.9 53.0 for 42 days 4. From 2 May 1131 802 525 42.9 50.3* for 21 days 2 & 3 & 4 1044** 782 525 40.1* 50* LSD (5%) 167 91 96 6.4 3.4 13.9 % reduction 19 % reduction 6.9 % reduction www.soilandwater.org.uk

Dick Godwin - Drainage the key factors and starting to address them Conclusions from Letcombe • For all treatments, grain losses were less than expected from the tiller loss in winter. • Losses after single waterlogging events ranged from 2% (after 47 days) to 16% (after 80 days). • Yield losses after 3 waterloggings at the seedling, tillering and stem elongation stages were additive, and totalled 19%. • In many treatments, grain loss was associated with lighter grain weights, • The importance of nitrogen fertilizer in maintaining a satisfactory plant nitrogen status was shown when nitrogen was with held before a 3-week waterlogging treatment during stem elongation. Land drainage and crop yield Crop failure – during growth, in this case ~25% loss Soya beans, Illinois - July 2008 Effect on crop growth – Denchworth Soil FDEU studies at Drayton 1970 -74 Winter Wheat Yield ~4.5 t/ha Drains & Moles + 1.0 t/ha Drains No moles & subsoiling + 0.6 t/ha Studies at Brooksby showed + 0.5t/ha from moling FDEU Annual Report 1975 Birds Eye lost 40% of pea yield in summer of 2007 due to poor trafficability www.soilandwater.org.uk

Dick Godwin - Drainage the key factors and starting to address them The Role of Drainage on Mechanisation Increasing water table depth: Increases soil strength & From :Profi o trafficability Less soil damage or compaction. o Easier& more effective field o operations. Increased number of available o work days, improved timeliness and establishment. Principal types of drainage problem 1. Surface water control (perched water table or top water) Impermeable layer 2. Groundwater table control (bottom water) Saturated zone Impermeable layer www.soilandwater.org.uk

Dick Godwin - Drainage the key factors and starting to address them Water budget Wat er out , Wat er in, Evaporat ion & Rainf all Transiprat ion Wat er st orage Drainage Soil constituents 20-30% AIR 45 - 48% MINERAL Sand/Silt/Clay 30-20% WATER 2 - 5% ORGANIC MATTER SOIL VOID SOIL SOLID www.soilandwater.org.uk

Dick Godwin - Drainage the key factors and starting to address them Sponge analogy • Saturation � All pores are filled with water Drainage • Field capacity � Some water has drained due to the forces of gravity Plants extracting water + evapotranspiration • Permanent wilting point � There is still some water but plants cannot apply enough suction to get it Soil-water relationships 50 Volumetric moisture content, % Saturation Saturation 40 Drainable porosity Available water 30 Field capacity 20 Permanent wilting point 10 0 Sand Sandy Clay Silty Clay Loamy Sandy Sandy Silt Sandy Silty sand loam clay loam clay silt loam clay clay loam loam After: Godwin and Dresser, 2003 www.soilandwater.org.uk

Dick Godwin - Drainage the key factors and starting to address them Soil-water relationships 50 Volumetric moisture content, % Saturation Drainable porosity Saturation 40 Drainable porosity Available water 30 Field capacity Field capacity 20 Permanent wilting point Permanent wilting point 10 0 Sand Loamy Sandy Sandy Silt Sandy Clay Silty Sandy Silty Clay sand loam silt loam clay loam clay clay clay loam loam After: Godwin and Dresser, 2003 Soil-water relationships 50 Volumetric moisture content, % Saturation Saturation 40 Drainable porosity Available water 30 Field capacity Field capacity 20 Permanent wilting point Permanent wilting point 10 0 Sand Sandy Clay Silty Clay Loamy Sandy Sandy Silt Sandy Silty sand loam clay loam clay silt loam clay clay loam loam After: Godwin and Dresser, 2003 www.soilandwater.org.uk

Dick Godwin - Drainage the key factors and starting to address them Soil-water relationships 50 Volumetric moisture content, % Saturation Drainable porosity Saturation 40 Drainable porosity Available water 30 Field capacity Field capacity Available water 20 Permanent wilting point Permanent wilting point 10 0 Sand Loamy Sandy Sandy Silt Sandy Clay Silty Sandy Silty Clay sand loam silt loam clay loam clay clay clay loam loam After: Godwin and Dresser, 2003 Perched water tables and storage capacity 50 Volumetric moisture content, % Saturation Saturation 40 Drainable porosity Available water 30 Field capacity Field capacity 20 Permanent wilting point Permanent wilting point 10 0 Sand Sandy Clay Silty Clay Loamy Sandy Sandy Silt Sandy Silty sand loam clay loam clay silt loam clay clay loam loam After: Godwin and Dresser, 2003 www.soilandwater.org.uk

Dick Godwin - Drainage the key factors and starting to address them Perched water tables and storage capacity Sand pit 50 Volumetric moisture content, % Saturation Saturation 40 Drainable porosity Available water 30 Field capacity Field capacity 20 Field conditions Permanent wilting point Permanent wilting point 10 Rivers Uck and Bourne catchments, 2003 0 Sand Loamy Sandy Sandy Silt Sandy Clay Silty Sandy Silty Clay sand loam silt loam clay loam clay clay clay loam loam After: Godwin and Dresser, 2003 Infiltration / soil wetting Coarse/Fine Fine/Coarse 0 mins www.soilandwater.org.uk

Dick Godwin - Drainage the key factors and starting to address them Infiltration / soil wetting Coarse/Fine Fine/Coarse 3 mins 0 mins 5 mins 8 mins Infiltration / soil wetting Coarse/Fine Fine/Coarse 8 mins Crack effect www.soilandwater.org.uk

Dick Godwin - Drainage the key factors and starting to address them Infiltration ~ soil type Main factors affecting infiltration • Soil type • Vegetation/surface cover 4.0 40 3.5 35 Infiltration rate (mm/hour) 3.0 30 2.5 25 Sandy loam 2.0 20 15 1.5 Loam 10 1.0 Clay loam 5 0.5 0.0 0 0 4 8 12 16 20 24 28 Time (hours) Infiltration ~ surface cover 2.5 150 Old permanent pasture or heavy mulch 4 to 8-year old permanent pasture 2.0 120 3 to 4-year old permanent Infiltration rate mm/hr pasture lightly grazed Permanent pasture moderately grazed 90 1.5 Hays Permanent pasture heavily grazed 60 1.0 Strip-cropped or mixed cover Weeds or grain 30 0.5 Clean tilled Bare ground 0 0.0 0 10 20 30 40 50 60 Time (min) 22 www.soilandwater.org.uk

Dick Godwin - Drainage the key factors and starting to address them Relationship between compaction and infiltration rate Infiltration rate (mm/hour) 1.42 1.58 1.62 1.62 After: Chyba, 2012 Soil Density g/cc Effect of organic matter • Silt loam soils in Missouri showed a decline in organic matter from 3.9% to 2.6% over a 60 year period. • This corresponded to a change in plastic limit moisture content from 27% to 22% and a less ideal working range. Ideal working range 3.9% Cemented/Hard Friable Plastic Liquid 2.6% Cemented/Hard Friable Plastic Liquid Dry Soil moisture content Wet After: Baver et. al., 1972 www.soilandwater.org.uk

Dick Godwin - Drainage the key factors and starting to address them Typical problems A less common scene Short term measures • Study “Old Drainage Plans” • Walk ditch drains • Check that tile drains, plastic pipes and mole drains are flowing • Clean blocked ditch and open drains • Flush pipe drains • Ensure outfall/arterial drains are functioning • Install “short term” mole/ditch/furrow drains if appropriate • Broadcast seed to establish cover and “pump out water” • Map damaged areas for repair later in the season/next opportunity www.soilandwater.org.uk

Dick Godwin - Drainage the key factors and starting to address them Clean ditches Drainage Maintenance: Pipe Jetting for Blockages 28 www.soilandwater.org.uk