No-Till: Making It Work - Nutrient Management

Table of Contents

1. Phosphorus and Potassium Stratification
2. Best Management Practices: Nitrogen
3. Best Management Practices: Phosphorus and Potassium
4. Best Management Practices: Lime
5. Available in Published Version of No-till

In no-till, nutrient requirements don't change. But in many cases, the type and timing of application practices do. The differences in the no-till seedbed conditions pose challenges for nutrient retention, fertilizer materials, application methods and timing of operations. There are fewer conventional application methods available - modifications to planting and nutrient application equipment can overcome these.

Before beginning a no-till system, soils should be in an acceptable pH range for crops grown.

Ideally, nutrient levels (phosphorus, potassium, magnesium, etc.) will be at a medium-high range.

Figure 1. Surface-applied nutrients waste money and increase risk to the environment.

Understanding the fertilizer materials and their activity in no-till conditions is a first step to making nutrient management work in no-till:

• urea or urea-based nitrogen fertilizers should never be broadcast and left on the soil surface, because a portion of the nitrogen could be lost to the air
• surface-applied fertilizers and manures are prone to runoff
• surface-applied manure and nitrogen-based fertilizers could lead to a more acidic soil surface
• soils may become more acidic if lime is not incorporated
• surface-applied or shallow banding of phosphorus and potassium could lead to stratification of these nutrients - this generally is not a problem, except in droughty conditions, as the roots tend to concentrate in this area, and residues preserve moisture, helping uptake
• mycorrhizal activity will increase, in turn increasing phosphorus uptake.

Phosphorus and Potassium Stratification

Nutrient stratification occurs under long-term no-till conditions. This means that a buildup of phosphorus (P) and potassium (K) occurs on or near the soil surface over time when the soil is managed in a no-till system. This stratification is caused by normal crop demands on the nutrients deeper in the soil profile, and the absence of incorporation.

The nutrient-rich layer with depleted zones below show up after three to five years of no-till management. When fertilizer is applied properly, however, nutrient stratification should not affect yields. To counter stratification, at least some of the phosphorus and potassium requirement should be applied in a band with or near the seed row. Because these two nutrients move very little in soil, plants use phosphorus and potassium applied in a band almost twice as efficiently as they use broadcast fertilizers.

Figure 2. No-till conditions help the growth of soil mycorrhizae. Soil mycorrhizae assist plant roots in obtaining nutrients (phosphorus) from the soil by increasing the area exploited by the roots.

Check the tables in OMAFRA Publication 296 for safe rates of nitrogen and potassium in starters.

The results from eight site-years showed a significant difference among nitrogen source, method and time of application treatments. The anhydrous ammonia and urea ammonium nitrate (UAN) soil-injected treatments gave considerably higher yields than urea ammonium nitrate and urea surface broadcast.

Best Management Practices: Nitrogen

At Planting

• some nitrogen with starter phosphorus and potassium will help emergence and improve phosphorus uptake
• some or all of the nitrogen requirement for corn can be applied at planting behind one of the tillage coulters - at least 4" from the row

Sidedress

• knifing in and injecting nitrogen are recommended sidedress practices in no-till
• some producers combine sidedress application with cultivation, manure application and herbicide application

We don't need to apply fertilizer to beans. But for corn we put dry starter behind one coulter and 40 lbs. of liquid 28% nitrogen behind the tillage coulter.

Charlie Bolton, Middlesex County

We've switched from anhydrous to liquid. It's easier to apply as sidedress.

Murray Lobb, Huron County

Best Management Practices: Phosphorus and Potassium

Broadcast

• phosphorus and potassium where required before starting no-till
• broadcast excess potassium requirements that cannot safely be banded

Band at Planting

• banding with seed or offset by 2" below and 2" beside seed
• over time in no-till, the increased mycorrhizal levels may allow phosphorus application rates to be reduced for corn and possibly beans

When we decided to get into no-till (1986), we tested the soil for phosphorus, potassium and pH levels. We broadcast where there were any problems. Now we test every three years and maintain the levels.

Elwin Vince, Kent County

Best Management Practices: Lime

Broadcast

• get your soil into shape before switching to no-till by broadcasting and incorporating lime - phosphorus, potassium and manure can be incorporated at the same time (lime mixed with the soil will do a better job at correcting acidity problems)
• once in no-till, incorporate lime if possible
• another option where lime is required is to surface-apply a tonne of lime regularly - coulters will do some incorporation

Lime won't move from where you put it, so surface applications won't help deep problems. Maintenance applications will work, but soil test is best.

Keith Reid, Ontario Ministry of Agriculture, Food and Rural Affairs

Available in Published Version of No-till

• Soil Sampling in No-till Systems
• Best Manure Management Practices - chart
• Other ways to include manure in the system
• Troubleshooting - chart