Corn Best Practices

Best Management Practices (BMPs) are the best recommended agronomic practices for growing a specified crop. These practices are based on research and experience and apply to corn under the specified agro-ecological conditions.
The recommended BMPs are not the only way to grow corn but are the best way determined by Netafim. The BMPs may change as additional proven research becomes available.

Agro-ecological situation
Climate
Conditions: Temperate, tropical and subtropical
Climatic requirement: Crop of warm climate and adequate moisture; the crop is sensitive to low temperature and frost
Radiation: 500 – 600 cal/ cm2/ day
Growing degree days: 2700 for 130 days crop
Rainfall: 600 to 800 mm/ annum
Relative humidity: 50 to 80%
Base temperature: 10 ºC
Optimum temperatures: for germination 18 – 20 ºC; for growth, daytime, 25 – 33 ºC and night time 17 – 23 ºC.
Comment: Delayed germination causes seed rot and reduced plant population. Heavy rains and water logging during pollination affects grain yield significantly.

Soil
Soil suitability: Fertile, deep, well drained clay loam to silty loam soils with good water holding characteristics
Soil pH: 7.0 to 8.5
Soil critical nutrient levels: 15 – 18 ppm NO3–N, 16 – 21 ppm P, 121 – 160 ppm K, 101 ppm Mg, 076 – 1.0 ppm Zn
Soil bulk density: 1.3 – 1.4 Mg/m3 - better favors root penetration, proliferation and soil water air relations
Groundwater table: Below 2.0 m
Critical soil salinity level (ECe): 1.7 dS/m above which yield decreases
Solis to avoid: waterlogged soils

Crop rotation
Proper rotation in corn system checks weeds, diseases & pests and avoids yield losses.
Without proper rotation, yield losses are 2 – 19% due to stalk rot disease.
Dry beans, soybean and potatoes are the best rotational crops for disease management.

Improved varieties
Along with yield potential maturity is of primary importance in selecting a variety and hybrid that will produce mature, high test weight grain during a normal growing season for a particular area.
Several hybrids are available for all types of corn and include double crosses, three-way crosses, single crosses, and modified crosses (or sister line crosses) depending on the country.

Planting material
Seed

Spacing
Row spacing: 0.70 m to 0.90 m
Plant spacing: 0.2 m
Optimum plant density: Varies between 70,000 to 80,000 plants/ ha

Seeding rate
Varies with cultivar, planting date, seed size and cost of production
Generally 20 to 25 kg/ha
Seeding by dibbling or by mechanical planters

Land prepartion
Clod free seedbed with good tilth to express its grain yield potential, subsurface drip irrigation (SDI) installation and optimal soil water air relations.
Destroy the hard pan if any using either chisel plough or a subsoiler to a depth of 35 – 40 cm.
Primary tillage by mould board plough or disc plough and secondary tillage by disc harrows, tyned harrows or rotavator to achieve proper tilth. 
Compost: 15 – 20 tons/ ha

Planting for better stand, yield and quality
Poor plant stand registers low yield
Soil temperature at planting: 15 – 18 °C
Planting depth: 3 to 5 cm under adequate soil moisture

Weed control
Managing weeds is critical for successful corn production.
Weeds compete for light, water, nutrients, etc., and reduce grain yields by 45% in Germany, 30% in Russia, 50% in India, 41 to 86% in USA and 40% in Indonesia, depending on the weed intensity.
Critical crop – weed competition period is initial 7 – 8 weeks.
Integrated weed control program involving crop rotation, manual weeding, good seedbed preparation, maintenance of optimum plant population, mechanical intercultivation and herbicide chemical applications.

Herbicides per hectare:
Before planting & at planting
Alachlor 2.8 – 3.4 kg
Atrazine 1.8 – 2.3 kg
Glyphosate 1.15 – 4.5 kg
After planting
Pendimethalin 0.95 – 1.9 kg
Glyphosate 1.15 – 4.5 kg
2, 4-D amine 0.26 – 0.52 kg
Paraquat 0.28 – 0.56 kg
Metribizin 0.085 – 0.170 kg

Irrigation system
Drip version: Surface or subsurface drip irrigation combined with fertigation.
Drip product: DripNet PC, Tiran, Dripline 17009, Super typhoon, UniRam and Python 22135.
Dripline spacing: 1.4 to 1.9 m with 1 lateral for every 2 crop rows
Emitter spacing: 0.4 m to 0.75 m - depending on soil texture
Emitter flow rate: 0.6 LPH, 1.0 LPH, 1.6 LPH and 2.0 LPH - depending on soil texture

Crop water requirement & irrigation scheduling
Estimate crop water requirements as a product of daily reference crop evapotranspiration (ETo) by Penman-Monteith method and crop coefficient for a given day according to the plant developmental stages.
Begin with 0.3 Kc of daily ETo in the initial period, raise it to 0.8 to 0.9 at vegetative stage, 1.2 at tasseling, silking & pollination stages, and decrease it to 0.5 at maturity of corn.
Irrigation scheduling using leaf water potential measurement by pressure chamber at 1.4 to 2.0 MPa at different stages enabled efficient use of water, fertilizer & energy inputs.
Daily crop water requirement: 6 to 7.5 mm/day
Seasonal crop water requirement: 350 to 800 mm - under range of environments

Fertigation
Apply mineral fertilizers based on the targeted yield, leaf analysis results, fertilizer experiment results, leaf deficiency symptoms, nutrient uptake, soil analysis results, nutrient recycling, etc.

Nutrient uptake:
191 kg N
89 kg P2O5
235 kg K2O
73 kg Mg
57 kg Ca
21 kg S for a yield of 9.5 tons/ha

Recommended nutrient dose: 120 to 180 kg N + 45 to 80 kg P2O5 + 30 to 80 K2O kg/ha
Critical levels in plant dry matter: 2.9% N, 0.25% P, 1.9% K, 0.15% Mg, 0.4% Ca, 0.15% S, 15 ppm Zn, 25 ppm Fe, 15 ppm Mn, 5 ppm Cu & 10 ppm B
For fertigation use water soluble fertilizers such as urea (46% N), potassium nitrate (13% N & 46% K2O), monoammonium phosphate (12% N & 61% P2O5) and ammonium nitrate (34% N).

Pests & diseases
Important pests: Flea beetles, seed corn maggots, leaf minor, spider mites, white grub, wire worm, cut worms, leaf aphids, army worm, stalk borer, root worm and European corn borer
Important diseases: Seedling blight, corn leaf blight, bacterial leaf blight, anthracnose leaf blight, maize dwarf mosaic, common rust, common smut, ear rot, kernel rot and grey leaf spot
Detect outbreaks and identify problem areas by routine patrols.
Monitor economic threshold levels and take up appropriate plant protection measures.

Harvesting
Corn is mature when the grain has about 30 – 32% moisture.
The best time to harvest depends on your harvest and storage system.
Timely harvesting of grain corn minimizes lodging, less ear droppage, avoids water logging and harvesting losses.

Grain yield
Under drip irrigation and fertigation a good commercial grain corn yield is 10 – 12 tons/ ha depending on length of growing season and variety (10 to 13 percent moisture).
Water utilization efficiency: Varying between 1.6 and 2.0 kg/m3