Objective:

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

Personnel:

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

Summary:

Boron treatments were applied at five rates detailed in Table 1. Three water use treatments were applied as the main factor, which included rainfed, half or deficit irrigation (50% ET), and sufficient or full irrigation (100% ET). The experimental design was a split plot with four replications. There was a full soil profile at the beginning of green up in spring as rainfall received in the fall and early spring was above average. Supplemental irrigation was applied when 35 percent of plant available water was used up. Rainfall events and amounts of irrigation applied per treatment are shown in Figure 1. Height measurements were taken prior to cutting when plants averaged 10% flowering. Two cuttings were made.

No significant differences were observed in height or yield data from boron fertilizer treatments (Table 3). Significant differences were observed for height and yield from water treatments (Table 4). The highest yield for total harvest was 2.16 T/A for 50 ET which was equivalent to the 100ET. This implies that the 50ET treatment did not impact yield as it allowed to store rainfall more efficiently (i.e., 60 DAE rainfall in Figure 1). Significant differences were observed for all but two nutrient analysis for hay quality from boron treatments for first harvest, but none for second harvest (Table 5). No significant differences were observed for hay quality from water treatments for first harvest, but significant differences were observed for second harvest (Table 6).

Table 1. Total B applied per treatment 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 applied 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: HybriForce-3400 Soil Test: 121-21-144
Seeding Date: 5/24/16 Fertilizer: 44-104-240-20S
Julian Date: 145 Boron Fertilizer: 0% Liquid - Agrisolutions
Seeding Rate: 20 lbs/A First Boron Application: 7/22/16
Previous Crop: Spring Wheat Second Boron Application: 8/3/16
Tillage: Conventional First Harvest: 7/27/16
Irrigation: Yes Second Harvest: 9/17/16
Soil Type: Fine Sandy Loam    

 

2016 Irrigation

Rainfall events and irrigation applied per treatment.

Table 3. Effects of Boron Fertilizer on Irrigated Alfalfa Yield.

Treatment 7/27 HT
in.		 7/27 YLD
T/A		 9/17 HT
in.		 9/17 YLD
T/A		 YLD Total
T/A
0 lb B 18.98 0.47 25.18 1.29 1.76
0.25 lb B begin + mid-season 19.94 0.59 24.42 1.25 1.84
0.5 lb B begin + mid-season 19.74 0.56 24.68 1.32 1.88
1 lb B begin + mid-season 21.56 0.81 25.09 1.31 2.12
2 lbs B begin season 20.31 0.67 26.05 1.40 20.6
LSD ns ns ns ns ns
Pr>F (0.05) - B 0.4312 0.0854 0.7620 0.8398 0.4581

Table 4. Effects of Water on Alfalfa Yield.

Treatment 7/27 HT
in.		 7/27 YLD
T/A		 9/17 HT
in.		 9/17 YLD
T/A		 YLD Total
T/A
Dryland/Rainfed 18.68 0.56 19.61 0.93 1.49
Half Irrigation (50 ET) 20.28 0.64 26.83 1.53 2.16
Full Irrigation (100 ET) 21.36 0.66 28.82 1.48 2.14
LSD 1.08 0.12 0.93 0.06 0.19
Pr>F 0.0004 0.0341 <0.0001 <0.0001 <0.0001

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

Table 5. Effects of Boron on Hay Quality

First Harvest - July 27

Treatment CP % ADF % NDF % TDN % RFV % B ppm
0 lb B 29.03 24.52 36.67 72.22 178.58 30.42
0.25 lb B begin + mid-season 28.38 25.66 37.58 70.98 173.42 32.67
0.5 lb B begin + mid-season 28.18 25.58 35.04 71.08 185.50 33.58
1 lb B begin + mid-season 29.53 28.33 40.56 68.11 156.42 38.92
2 lbs B begin season 28.87 26.65 37.98 69.92 170.08 42.00
LSD ns 1.72 2.45 1.86 ns 2.39
Pr>F (0.05) - B 0.5295 0.0424 0.0483 0.0430 0.0672 <0.0001

 

Second Harvest - September 17

Treatment CP % ADF % NDF % TDN % RFV % B ppm
0 lb B 28.36 30.65 35.51 65.61 172.58 29.67
0.25 lb B begin + mid-season 26.84 30.26 35.93 66.04 171.75 38.75
0.5 lb B begin + mid-season 27.39 30.07 36.80 66.26 168.17 42.42
1 lb B begin + mid-season 27.21 31.45 37.19 64.74 164.42 48.58
2 lbs B begin season 26.66 30.86 37.68 65.38 160.75 43.25
LSD ns ns ns ns ns 5.5
Pr>F (0.05) - B 0.1999 0.7640 0.3606 0.7596 0.4952 <0.0001

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

Table 6. Effects of Water on Hay Quality

First Harvest - July 27

Treatment CP % ADF % NDF % TDN % RFV % B ppm
Dryland/Rainfed 28.71 26.35 38.31 70.26 168.65 32.60
Half Irrigation (50 ET) 29.20 26.59 37.73 69.99 171.25 35.70
Full Irrigation (100 ET) 28.48 25.52 36.65 71.14 178.50 38.25
LSD ns ns ns ns ns ns
Pr>F (0.05) - ET 0.3546 0.5045 0.4391 0.5081 0.3958 0.1333

 

Second Harvest - September 17

Treatment CP % ADF % NDF % TDN % RFV % B ppm
Dryland/Rainfed 29.22 27.90 33.63 68.58 188.55 27.75
Half Irrigation (50 ET) 26.63 31.74 38.17 64.42 157.55 43.80
Full Irrigation (100 ET) 26.03 32.33 38.07 63.81 156.50 50.05
LSD 1.24 0.90 3.01 0.98 14.76 5.45
Pr>F (0.05) - ET 0.0001 0.0002 0.0011 0.0002 0.0002 0.0002

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