## FERTILIZER RECOMMENDATIONS

– 201 1

NITROGEN (N)

Crop Soil Type Nitrogen Rate (lbs N/acre) Plant

- cane Light 60

– 80 Plant

- cane Heavy 80

– 100 Stubble Light 80

– 100 Stubble Heavy 100

- 120

 For efficient nitrogen utilization, it is important that soil pH is in balance (ideally 6.2) and adequate P & K are available.

 Recommendations are based on tests where UAN 32% was the primary nitrogen source

.

 R ecommendations are based on data with current varieties and on a wide range o f soil types at locations throughout the industry on plant

- cane through third stubble crops

.

 Higher than recommended rates of nitrogen may increase tons of cane per acre , but also decrease sugar per ton of cane

. R ecommended rates will maximize sugar per acre yields with optimum sugar per ton of cane

.

 Apply nitrogen between April 1 and April 30.

 T here is an association between rust severity and excess levels of nitrogen.

### POTASSIUM ( as K 2 

### O)

Soil test category Plant

- cane Stubble

- cane

---------- ------------ lbs/acre

-------------- ---------- Very low 120 140 Low 110 120 Medium 80 80 High 0 0 Very high 0 0

 Recommendations are based on soil tests.

 When prices are high consider applying only when soil test levels are low or very low

. Although not specifically recommended above, if one is not considering the application of potassium at all, it would be wise to consider applying at least 60 lbs/acre to those fields testing very low or low.

 Sugarcane utilizes approximately 3 lbs of K 2 O per ton of cane

.

 Response is more likely in a s tubble crop than in a plant

- cane crop.



### PHOSPHOROUS ( as P 2 

### 0 5 

### )

Soil test category Plant

- cane Stubble

- cane

---------- ------------ lbs/acre

-------------- ---------- Very low 50 60 Low 45 50 Medium 40 40 High 0 0 Very high 0 0

 Recommendations are based on results of soil tests.

 When prices are high consider applying only when soil test levels are low or very low.

 Sugarcane utilizes approximately 1 lb of P 2 O 5 per ton of cane with availability dependent upon soil pH & soil type. Optimal soil pH for best phosphorous availability is 6.2.

 There is an association between rust severity and excess levels of phosphorous.

### SULFUR (S)

Soil test category Plant

- cane Stubble

- cane

---------- ------------ lbs/acre

-------------- ---------- Low 24 24 High 0 0

 Recommendations are based on results of soil tests.

 Stubble cane is more likely to respond tha n plant

- cane.

 Response is more likely on medium

- heavy to heavy textured soils.

 There is an association between rust severity and excess levels of sulfur.



### MICRONUTRIENTS

Zinc (Zn)

Soil test category Application Rate

------- lbs/acre

---------- Very low (<1 ppm) 6 Low (< 2.25 ppm) 3

 Apply only if soil tests or tissue analyses indicate deficiencies.

### LIME

C heck lime requirements by conduct ing soil tests. Liming is primarily a method of correcting soil pH , but there are several other benefits to include:

 To adjust soil pH to improve fertilizer use efficiency by maximizing nutrient availability

.

 To suppl y calcium, an essential plant food nutrient. If magnesium is deficient, use dolomitic limestone.

 To reduce aluminum and manganese toxicity.

 To enhance the activity of soil microorganisms.

 To improve the activity of soil applied herbicides.

 To decrease the total amount of lime applie d , consider variable rate lime applications.

Lime when:

 Soil pH <5.8 on sandy loam & silt loam soils.

 Soil pH <5.2 on clay loam & clay soils.

 The lime rate should be based on soil test and ideally should raise soil pH to 6.2.

 It is ideal to b roadcast lime to fallow fields or in crop during the fall or winter.

 Apply lime after precision leveling

.

How Long Will it Take for Lime to Work?

 The biggest change in pH will occur within 3

- 4 months. The pH may continue to increase for 6

- 12 months.

1 Prepared by Dr. Kenneth Gravois, Sugarcane Specialist, LSU AgCenter, from information obtained from research conducted by Drs. Benjamin L. Legendre, Brenda Tubana, Sonny Viator, Jim Wang and Jeff Hoy, LSU AgCenter ; and Drs. Rich Johnson, Ryan Viator, Paul White, Mike Grisham and Edward Richard, Jr., USDA

- ARS, Sugarcane Research Laboratory, in cooperation with County Agents, Louisiana Cooperative Extension Service.