Objective:

To evaluate the effects of boron fertilizer rate and timing on alfalfa yield and quality.

Personnel:

J.A. Torrion, E. Glunk, R.N. Stougaard, A. Sapkota, J. Garner

Summary:

Boron treatments were applied at five rates with amounts and timing detailed in Table 1. The experimental design was a randomized complete block with four replications. There was a full soil profile beginning at green up; rainfall received in the fall and early spring was above average. From the first green up to the last cutting (April to October 24, 2016) 14.75 inches of rain was received (October received record precipitation of 5.48 inches). Supplemental irrigation was applied when needed from June to September. Height measurements were taken prior to cutting when plants achieved 10% flowering. Three cuttings were made.

No significant differences were observed for height or yield (Table 3). Average total yields were 5.4 T/A. First harvest had the highest yield at 2.4 T/A.

Significant differences were observed in boron uptake and alfalfa quality (Table 4). Crude protein was highest at second harvest. Significance in boron uptake was observed for all three harvests.

Table 1. Total B applied per treatment year and application timing.

Treatment Total B (lb/A/year) Application
1 Untreated Check None
2 0.5 0.25 lb/A applied at 3-in regrowth in early spring +
0.25 lb/A at 3-in regrowth after first cutting
3 1.0 0.50 lb/A applied at 3-in regrowth in early spring +
0.50 lb/A at 3-in regrowth after first cutting
4 2.0 1.0 lb/A applied at 3-in regrowth in early spring +
1.0 lb/A at 3-in regrowth after first cutting
5 2.0 2.0 lb/A applied at 3-in regrowth in early spring

Table 2. Materials and Methods.

Variety: Pioneer 58V09 Fertilizer: 0-0-62
Seeding Date: 5/15/14 Sulfur Fertilizer: 21-0-0-24S
Julian Date: 135 Boron Fertilizer: 10% Liquid- Agrisolutions
Seeding Rate: 12 lb/A First Boron Application: 4/11/16
Previous Crop: Barley Second Boron Application: 7/5/16
Tillage: Conventional First Harvest: 6/13/16
Irrigation: Yes Second Harvest: 8/2/16
Soil Type: Fine Sandy Loam Third Harvest: 10/24/16
Soil Test: 22-18-88    

Table 3. Effects of Boron Fertilizer on Alfalfa Yield.

Treatment 6/13 HT
in.		 6/13 YLD
T/A		 8/2 HT
in.		 8/2 YLD
T/A		 10/24 HT
in.		 10/24 YLD
T/A		 YLD Total
T/A
0 lb B 44 2.0 33 1.6 28 1.4 5.1
0.25 lb B begin + mid-season 43 2.6 32 1.6 28 1.4 5.6
0.5 lb B begin + mid-season 45 2.6 33 1.5 29 1.4 5.4
1 lb B begin + mid-season 46 2.5 33 1.6 29 1.5 5.5
2 lb B begin season 43 2.4 35 1.5 29 1.5 5.4
Mean 44 2.4 33 1.6 28 1.4 5.4
CV 7 20 4 11 4 6 7
LSD ns ns ns ns ns ns ns
Pr>F 0.4898 0.4502 0.0726 0.9166 0.5289 0.2741 0.4377

HT: height; YLD: yield; ns: non-significant; B: boron (amount applied begin season same as mid-season)