Project Leader:

Jessica Torrion (PI), Bob Stougaard (Co-PI)

Project Personnel:

John Garner, Brook Bohannon, Emily Glunk

Objective:

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

Summary:

Boron treatments were applied to evaluate the impact on alfalfa yield and quality, which included 5 rates of 0, 0.25, 0.5, 1, and 2 lbs/A at begin season (April 16) and 4 rates of 0, 0.25, 0.5, and 1 lbs/A at midseason (June 23). The experimental design was a randomized complete block with five treatments and four replications. Treatments were applied when the crop averaged 2-3 inches in height. There was a full soil profile beginning of green up in spring as rainfall received in the fall and early spring was above average. From the first green up to the last cutting (April to September, 2015) only 3.5 inches of rain was received and supplemental irrigation was needed. Height measurements were taken prior to cutting when plants averaged 10% flowering. Three cuttings were made.

No significant differences were observed for height or yield (Table 2). Average total yields were 6.1 T/A. First harvest had the highest yield at 3 T/A while third had the lowest at 1.4 T/A. The initial soil test for Boron in spring was low, but the average Boron tissue test (Table 3) were near or at sufficiency level for low Boron application, thus, no consistent hay quality trend can be observed. Alfalfa Boron trial was conducted on the second year of alfalfa establishment. Future studies will consider irrigation as an additional factor to Boron uptake and hay quality.

Table 1. Materials and Methods.

Seeding Date: 5/15/14 First Application Date: 4/16/15
Julian Date: 135 Julian Date: 106
Seeding Rate: 12 lbs/A Second Application Date: 6/23/15
Previous Crop: Barley Julian Date: 174
Tillage: Conventional First Harvest Date: 6/10/15
Irrigation: Yes Julian Date: 161
Soil Type: Fine Sandy Loam Second Harvest Date: 7/14/15
Soil Test: 30-21-201 Julian Date: 195
Fertilizer: Liquid Boron 10% - Agrisolutions Third Harvest Date: 10/2/15
Rates: 0.0, 0.25, 0.5, 1.0, 2.0 lbs/A Julian Date: 275

Table 2. Effects of Boron Fertilizer on Alfalfa Yield - 2015.

Treatment 6/10 HT
in. 		6/10 YLD
T/A 		7/14 HT
in. 		7/14 YLD
T/A 		10/2 HT
in. 		10/2 YLD
T/A 		Total YLD
T/A
0 lbs B 27 3.0 22 1.9 21 1.6 6.5
0.25 lb. B begin + mid-season 28 3.1 22 1.7 21 1.5 6.2
0.5 lb B begin + mid-season 27 2.9 21 1.7 23 1.4 6.0
1 lb B begin + mid-season 29 3.0 21 1.6 21 1.4 6.0
2 lbs B begin season 28 3.0 20 1.6 20 1.3 5.9
Mean 28 3.0 21 1.7 21 1.4 6.1
CV 8 11 10 9 17 13 8
LSD ns ns ns ns ns ns ns
Pr>F 0.5978 0.9730 0.5875 0.0855 0.8307 0.3720 0.4408

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

Table 3. Boron Uptake and Hay Quality - 2015.

Treatment CP % ADF % NDF % TDN % RFV % B ppm
                      First Harvest - June 10
0 lb B  25.6 30.0 44.1 66.3 138 25
0.25 lb B begin + mid-season 25.7 27.7 38.8 68.8 161 34
0.5 lb B begin + mid-season 27.7 28.6 36.0 67.8 172 30
1 lb B begin + mid-season 22.9 33.0 38.5 63.1 153 30
2 lbs B begin season 28.9 30.4 34.7 65.9 175 38
                     Second Harvest - July 14
0 lb B 22.7 35.0 40.3 60.9 142 25
0.25 lb B begin + mid-season 22.4 36.3 42.5 59.5 133 33
0.5 lb B begin + mid-season 22.8 37.8 45.7 57.9 121 34
1 lb B begin + mid-season 28.3 28.2 31.9 68.2 195 30
2 lbs B begin season 25.6 34.5 40.2 61.5 144 38
                   Third Harvest - October 2
0 lb B 25.6 22.1 29.1 74.8 229 32
0.25 lb B begin + mid-season 27.4 24.3 29.0 72.5 224 41
0.5 lb B begin + mid-season 25.0 25.7 31.0 71.0 207 32
1 lb B begin + mid-season 24.7 22.9 30.4 74.0 217 43
2 lbs B begin season 25.1 25.8 29.7 70.8 215 40

CP: crude protein; ADP: acid detergent fiber; NDF: neutral detergent fiber; TDN: total digestible nutrients; RFV: relative feed value; B: boron (amount applied begin season same as mid-season)