Land Formation and Water Management. Whitney Brim-DeForest Rice Advisor Rice Production Workshop 2018

Transcription

1 Land Formation and Water Management Whitney Brim-DeForest Rice Advisor Rice Production Workshop 2018

2 Land Formation: Key Concepts 1. Land leveling (grade of the land close to 0%): Allows for improved water management Better weed control Due to movement of soil, fertility issues may arise 2. Levees: Allow for division of fields into smaller areas ( checks ) Can make water management easier Spacing must be considered for irrigation management Irrigation is gravity-fed, so slope and fall between checks is important

3 Land Leveling Laser leveling became widespread in the 1970 s: Resulting shift from contour to parallel levees Larger field sizes, increased yields by about 10% Increased efficiency of irrigation and equipment use GPS leveling: more recent More accurate than laser leveling Less impacted by weather (dust and wind)

4 Purposes of Water Management The general goals of water management are: Supply water to the crop Establish an optimum plant population Suppress weeds Provide for pesticide applications Conserve nutrients Protect against cold weather Protect water quality Manage salinity

5 Evapotranspiration: EVAPORATION + TRANSPIRATION Amount the crop takes up through the roots and transpires from leaf surfaces into the atmosphere Varies with seasonal length, so an easy way to save water in rice is to grow shorter season varieties Climatic factors: solar radiation, wind and temperature ACRE FEET PER ACRE: APPROX 2.75

6 Percolation: Down through the soil profile Most rice soils have clay and/or hardpan in the subsoil If deep percolation is excessive, rice may be a poor crop choice Seepage: Lateral movement out of the field Seepage occurs in all soils, but is more of a problem in course texture soils which have high hydraulic conductivity. ACRE FEET PER ACRE: APPROX

7 Drainage/Spill: During and at the end of the season Accounts for balance of delivered use Varies with use of leveling and mandated water holding required for pesticide use ACRE FEET PER ACRE: APPROX

8 Seasonal Water Use Acre feet per acre Evapotranspiration (Et) 2.75 Percolation/seepage Drainage Total Reducing Consumptive Use: Difficult to make major changes to consumptive water use without significantly reducing yield. 1) Use shorter duration varieties which reduces the period that rice is actively growing and transpiring water. 2) Plant later in the season. This increases the rate of plant growth and development. Both reduce consumptive water use by about 1 over the season Reducing Water Withdrawal: Reducing tailwater spill (drainage), if salinity is not a problem Percolation is not usually a problem in heavy clay soils that rice. If fields do have high percolation rates, it may be wise to take these fields out of rice production. Seepage can be reduced by maintaining good levees around fields.

9 Water Management Systems Flow-through System

10 Water Management Systems Recirculating Tailwater Recovery System

11 Water Management Initial Flood-Up: Usually flooded at the beginning of the season 4-6 Deeper in some cases (organic) Flood up as quickly as possible, to avoid weed germination before the flood Drain for stand establishment (Leathers method) Especially important if windy Limits herbicides that can be utilized Allows rice to peg, root into the ground Drain field immediately after sowing up to two days after sowing Drain for 3 to 5 days, depending on temperature and growth of roots Rapidly re-flood

12 Water Management Pinpoint Drain: Occurs around the 3-4 leaf stage of rice For foliar herbicide application Water may or may not be fully drained, just enough to expose weeds Water may remain off the field for 3-4 days, sometimes longer Permanent Flood (4-6 ): Should occur as early as possible in the season To reduce weed pressure AND Optimize rice growth

13 Water Management Blanking Protection: Blanking occurs when pollen is damaged by cool night-time temperatures It is the major temperature related factor reducing yields in California Mitigated by raising the water level during panicle initiation (PI) Water temperatures are warmer than air temperatures Pre-Harvest Drainage: Fields are typically drained 2-4 weeks before harvest Allows for movement of heavy equipment onto field

14 Cold-Water Effects 1st Tiller PI Boot 50% Heading DAP North (inlet) South INTAKE Head (cm) Seeds per panicle % Blanks Yield (lb) North (inlet) (green) South

15 Cold-Water Effects INTAKE Management: Growers should be aware of fields with colder water intakes Using a warming basin to warm water coming out of the well or irrigation canal before putting it into the field

16 Salinity Rice is sensitive during the seedling and pollination stages Most irrigation water used on rice in California has low salt (<0.7 ds/m) Some water sources that include drain and well water can go much higher Sacramento River water is low in salt (between 0.13 and 0.37 ds/m) Yield reductions associated with salinity of >0.9 ds/m

17 Managing Salinity Irrigation water should have an EC below 0.6 ds/m Change water flow path Early in the season when salinity is highest, allow for spillage and maintain higher water levels Smaller fields and multiple side inlets Herbicide selection Avoid those with long water-holding periods

18 Water Quality What is the contribution of rice farming to surface water quality in CA? UC Davis researchers studied: Nutrients (ammonium, potassium, phosphorous, etc) Solids (Total Dissolved Solids, Total Suspended Solids, etc) Main area of concern: Pesticide movement into water Contamination of drinking water (particularly in Sacramento)

19 Water leaving rice fields (tailwater): Higher concentrations of dissolved organic carbon (DOC) Higher concentration of total suspended solids (TSS) Higher total dissolved solids (TDS) Slightly elevated ammonium and potassium

20 Established for every pesticide registered for use in CA rice California-specific guidelines COMMON TRADE NAME 1 WATERHOLD ACTIVE INGREDIENT TIME INSECTICIDES: Sevin Brand 4F Carbaryl 0-days DuPont TM Coragen Chlorantranilprole 14-days Belay Insecticide Clothianidin 14-days Mustang Max Insecticide (s)-cypermethrin 7-days Dimlin 2L Insect Growth Regulator Diflubenzuron 14-days Warrior Insecticide Lambda cyhalothrin 7-days Malathion 8 Malathion 4-days FUNGICIDES: Quadris Flowable Fungicide Azoxystrobin 14-days Tilt (propiconazole) Stratego Fungicide Propiconazole/ Trifloxystrobin 7-days HERBICIDES: Solution Water Soluble 2,4-D 0 - days Londax Herbicide Bensulfuron-methyl 7-days static BUTTE Herbicide Benzobicyclon 20 - days 5-days static Shark Carfentrazone-ethyl 30-days release: Herbicide less closed system Cerano 5 MEG Bombard TM Herbicide Clomazone 14-days Clincher CA Clincher Granule Cyhalofop-butyl 0 or 7-days Sandea Herbicide Halosulfuron-methyl 0 - days Granite SC & GR Penoxsulam 0-days Stam 80 EDF Abolish 8EC Bolero UltraMax League MVP Grandstand CA Herbicide Propanil Thiobencarb Triclopyr TEA 7-days: less closed system See table on reverse 20-days: less closed system

21 Water-Holding Periods Allows for dissipation of pesticide in water in the field

22 Rice Pesticides Program (RPP) Started in 1990 Currently only monitoring one chemical: Thiobencarb (Abolish, Bolero, League MVP) Monitored by sampling drains and water going into the city of Sacramento When exceedances have occurred, industry has quickly addressed the issue

23 Groundwater Quality Little contamination of groundwater by nitrate leaching from rice fields Likely due to: The low permeability of soils Fertilizer N is applied as ammonium or a form that quickly concerts to ammonium. Fertilizer N is not applied as nitrate. Soils remain flooded or saturated for much of the season. This creates anaerobic conditions which prevents the ammonium from nitrifying to form nitrate.

24 Map of the Sacramento Valley delineating rice production areas and locations and types of wells selected to assess groundwater impacts within and near rice lands

25 Questions?