Figure 1.
Soil volumetric water content (VWC) for the different combinations of drip (DR) and micro-sprinkler (MS) irrigation with different fertilizer levels (25, 50, 100, and 200%) in 2016. Rain events are shown as vertical bars. From 14 May 2016 to 22 June 2016, the irrigation system was being tested and the irrigation was controlled by hand, trying to keep the VWC above 25%. After 23 June 2016, the automated irrigation network was turned on, following the thresholds established (from early May to early August: VWC threshold of 25%; from early August to mid-September: VWC threshold of 20%; from mid-September to late September: VWC threshold of 15%; late September to December: irrigation off). Values are the average of four sensors (two at 20 cm and two at 40 cm depth).
Figure 1.
Soil volumetric water content (VWC) for the different combinations of drip (DR) and micro-sprinkler (MS) irrigation with different fertilizer levels (25, 50, 100, and 200%) in 2016. Rain events are shown as vertical bars. From 14 May 2016 to 22 June 2016, the irrigation system was being tested and the irrigation was controlled by hand, trying to keep the VWC above 25%. After 23 June 2016, the automated irrigation network was turned on, following the thresholds established (from early May to early August: VWC threshold of 25%; from early August to mid-September: VWC threshold of 20%; from mid-September to late September: VWC threshold of 15%; late September to December: irrigation off). Values are the average of four sensors (two at 20 cm and two at 40 cm depth).
Figure 2.
Soil volumetric water content (VWC) for the non-irrigated treatments and for the different combinations of drip (DR) and micro-sprinkler (MS) irrigation with different fertilizer levels (25, 50, 100, and 200%) in 2017. Rain events are shown as vertical bars. The automated irrigation network was activated in 12 May 2017, with the intent of following the thresholds established (from early May to early August: VWC threshold of 25%; from early August to mid-September: VWC threshold of 20%; from mid-September to late September: VWC threshold of 15%; from late September to December: irrigation off). The system was damaged and deactivated after 28 July 2017 because of a lightning strike. For the irrigated treatments, the values are the average of four sensors (two at 20 cm and two at 40 cm depth). For the non-irrigated, values the are averages of 32 sensors (16 at 20 cm and 16 at 40 cm depth).
Figure 2.
Soil volumetric water content (VWC) for the non-irrigated treatments and for the different combinations of drip (DR) and micro-sprinkler (MS) irrigation with different fertilizer levels (25, 50, 100, and 200%) in 2017. Rain events are shown as vertical bars. The automated irrigation network was activated in 12 May 2017, with the intent of following the thresholds established (from early May to early August: VWC threshold of 25%; from early August to mid-September: VWC threshold of 20%; from mid-September to late September: VWC threshold of 15%; from late September to December: irrigation off). The system was damaged and deactivated after 28 July 2017 because of a lightning strike. For the irrigated treatments, the values are the average of four sensors (two at 20 cm and two at 40 cm depth). For the non-irrigated, values the are averages of 32 sensors (16 at 20 cm and 16 at 40 cm depth).
Figure 3.
Soil volumetric water content (VWC) for the non-irrigated treatments and for the different combinations of drip (DR) and micro-sprinkler (MS) irrigation with different fertilizer levels (25, 50, 100, and 200%) in 2018. Rain events are shown as vertical bars. The automated irrigation network was activated on 7 May 2018, with the intent of following the thresholds established (from early May to early August: VWC threshold of 25%; from early August to mid-September: VWC threshold of 20%; from mid-September to late September: VWC threshold of 15%; from late September to December: irrigation off). However, the system was damaged and the data were not recorded from 8 August 2018 to 5 September 2018. For the irrigated treatments, the values are the average of four sensors (two at 20 cm and two at 40 cm depth). For the non-irrigated treatment, the values are the average of 32 sensors (16 at 20 cm and 16 at 40 cm depth).
Figure 3.
Soil volumetric water content (VWC) for the non-irrigated treatments and for the different combinations of drip (DR) and micro-sprinkler (MS) irrigation with different fertilizer levels (25, 50, 100, and 200%) in 2018. Rain events are shown as vertical bars. The automated irrigation network was activated on 7 May 2018, with the intent of following the thresholds established (from early May to early August: VWC threshold of 25%; from early August to mid-September: VWC threshold of 20%; from mid-September to late September: VWC threshold of 15%; from late September to December: irrigation off). However, the system was damaged and the data were not recorded from 8 August 2018 to 5 September 2018. For the irrigated treatments, the values are the average of four sensors (two at 20 cm and two at 40 cm depth). For the non-irrigated treatment, the values are the average of 32 sensors (16 at 20 cm and 16 at 40 cm depth).
Figure 4.
Total N removed per tree for the different fertilizer levels (25, 50, 100, and 200%) of the “Julyprince” peaches in 2016, 2017, and 2018. For each removal event (different colors), the means are shown inside the bars. z Means followed by a different letter within a removal event are significantly different by Tukey’s honestly significant different test, P ≤ 0.05. Means without letters indicate non-statistical differences, P > 0.05.
Figure 4.
Total N removed per tree for the different fertilizer levels (25, 50, 100, and 200%) of the “Julyprince” peaches in 2016, 2017, and 2018. For each removal event (different colors), the means are shown inside the bars. z Means followed by a different letter within a removal event are significantly different by Tukey’s honestly significant different test, P ≤ 0.05. Means without letters indicate non-statistical differences, P > 0.05.
Figure 5.
Total N removed per tree for the different irrigation levels (irrigated vs. non-irrigated) of “Julyprince” peaches in 2016, 2017, and 2018. For each removal event (different colors), the means are shown inside the bars. z Means followed by a different letter within a removal event are significantly different by Tukey’s honestly significant different test, P ≤ 0.05. Means without letters indicate non-statistical differences, P > 0.05.
Figure 5.
Total N removed per tree for the different irrigation levels (irrigated vs. non-irrigated) of “Julyprince” peaches in 2016, 2017, and 2018. For each removal event (different colors), the means are shown inside the bars. z Means followed by a different letter within a removal event are significantly different by Tukey’s honestly significant different test, P ≤ 0.05. Means without letters indicate non-statistical differences, P > 0.05.
Figure 6.
Total N removed per tree for the different irrigation systems (drip vs. micro-sprinkler) of “Julyprince” peaches in 2016, 2017, and 2018. For each removal event (different colors), the means are shown inside the bars. z Means followed by a different letter within a removal event are significantly different by Tukey’s honestly significant different test, P ≤ 0.05. Means without letters indicate non-statistical differences, P > 0.05.
Figure 6.
Total N removed per tree for the different irrigation systems (drip vs. micro-sprinkler) of “Julyprince” peaches in 2016, 2017, and 2018. For each removal event (different colors), the means are shown inside the bars. z Means followed by a different letter within a removal event are significantly different by Tukey’s honestly significant different test, P ≤ 0.05. Means without letters indicate non-statistical differences, P > 0.05.
Table 1.
Soil analysis from the experimental field (0–40 cm depth) at the Dempsey Farm, University of Georgia, Griffin, GA. Samples were taken in April of 2016 before any fertilizer treatments were applied (n = 48).
Table 1.
Soil analysis from the experimental field (0–40 cm depth) at the Dempsey Farm, University of Georgia, Griffin, GA. Samples were taken in April of 2016 before any fertilizer treatments were applied (n = 48).
pH | P | K | Mg | Ca | B | Zn | Mn | Fe | Cu | NO3-N | NH4-N | Cation Exchange Capacity (CEC) | Organic Matter (OM) |
---|
kg·ha−1 | cmol·kg−1 | % |
---|
5.95 | 58.9 | 188.4 | 184.8 | 866.4 | 0.5 | 3.3 | 22.4 | 66.2 | 1.4 | 17.0 | 5.4 | 4.84 | 1.51 |
Table 2.
Precipitation (mm) from January to December in 2016, 2017, and 2018 and the historic normal (average from 1981 to 2010) at the Dempsey Farm, Griffin, GA.
Table 2.
Precipitation (mm) from January to December in 2016, 2017, and 2018 and the historic normal (average from 1981 to 2010) at the Dempsey Farm, Griffin, GA.
| January | February | March | April | May | June | July | August | September | October | November | December | Total |
---|
2016 | 110 | 125 | 66 | 174 | 67 | 77 | 66 | 69 | 159 | 1 | 69 | 159 | 754 |
2017 | 247 | 66 | 53 | 97 | 91 | 194 | 91 | 112 | 130 | 207 | 28 | 79 | 952 |
2018 | 103 | 98 | 133 | 118 | 145 | 134 | 103 | 106 | 84 | 132 | 164 | 267 | 940 |
1981–2010 | 112 | 104 | 146 | 113 | 96 | 96 | 150 | 131 | 91 | 83 | 99 | 99 | 947 |
Table 3.
Soil analyses for NH4–N, NO3–N, P, and K for the different fertilizer levels (25, 50, 100, and 200%) and sample depth (0–20 and 20–40 cm) in 2017, 2018, and 2019 from the Dempsey Farm, University of Georgia, Griffin, GA. In 2017 and 2019, soil samples were taken before fertilizer application (recommended practice). In 2018, soil samples were taken two days after fertilizer application, displaying elevated values relative to the samples taken in 2017 and 2019, because of the sampling time.
Table 3.
Soil analyses for NH4–N, NO3–N, P, and K for the different fertilizer levels (25, 50, 100, and 200%) and sample depth (0–20 and 20–40 cm) in 2017, 2018, and 2019 from the Dempsey Farm, University of Georgia, Griffin, GA. In 2017 and 2019, soil samples were taken before fertilizer application (recommended practice). In 2018, soil samples were taken two days after fertilizer application, displaying elevated values relative to the samples taken in 2017 and 2019, because of the sampling time.
Nutrient | Fertilizer Level | Sample Depth (cm) | P Value |
---|
25% | 50% | 100% | 200% | 0–20 | 20–40 | Fertilizer Level | Sample Depth |
---|
kg·ha−1 |
---|
April 2017 |
---|
NH4–N | 2.3 | | 2.4 | | 4.7 | | 7.6 | | 4.8 | | 3.7 | | 0.091 | 0.523 |
NO3–N | 17.2 | b z | 22.4 | b | 30.9 | ab | 48.3 | a | 31.4 | | 28.0 | | <0.001 | 0.533 |
P | 57.7 | c | 60.0 | bc | 85.0 | ab | 105.4 | a | 107.9 | a | 46.2 | b | <0.001 | <0.001 |
K | 155.1 | | 144.1 | | 141.6 | | 156.4 | | 161.1 | a | 137.5 | b | 0.223 | <0.001 |
| April 2018 |
NH4–N | 15.5 | c | 43.5 | bc | 47.7 | b | 123.0 | a | 86.1 | a | 28.7 | b | <0.001 | <0.001 |
NO3–N | 37.3 | b | 45.6 | ab | 47.7 | ab | 63.6 | a | 45.0 | | 52.1 | | 0.019 | 0.230 |
P | 69.7 | c | 87.5 | c | 123.2 | b | 165.8 | a | 155.3 | a | 67.8 | b | <0.001 | <0.001 |
K | 183.3 | c | 224.6 | bc | 245.2 | b | 322.6 | a | 289.4 | a | 198.5 | b | <0.001 | <0.001 |
| May 2019y |
NH4–N | 7.3 | | 6.7 | | 7.9 | | 8.4 | | 7.6 | | N/A | | 0.592 | N/A |
NO3–N | 4.4 | | 2.9 | | 6.7 | | 2.1 | | 4.0 | | | 0.058 |
P | 89.9 | c | 104.8 | bc | 138.3 | b | 194.0 | a | 131.8 | | | <0.001 |
K | 146.7 | | 151.1 | | 163.0 | | 160.9 | | 155.4 | | | 0.548 |
Table 4.
Dry weight (DW) and N concentration in the different removal events for the different fertilizer levels (25, 50, 100, and 200%) for trees of “Julyprince” peaches in 2016, 2017, and 2018.
Table 4.
Dry weight (DW) and N concentration in the different removal events for the different fertilizer levels (25, 50, 100, and 200%) for trees of “Julyprince” peaches in 2016, 2017, and 2018.
Removal Event | Dry Weight (g/tree) | P Value |
---|
25% | 50% | 100% | 200% |
---|
Pruning Leaf July 2016 | 360.9 | | 382.6 | | 355.3 | | 340.9 | | 0.888 |
Pruning Stem July 2016 | 270.8 | | 287.5 | | 270.1 | | 256.0 | | 0.895 |
Defoliation October 2016 | 1080.9 | | 1121.4 | | 980.6 | | 1413.8 | | 0.181 |
Pruning February 2017 | 875.2 | | 992.4 | | 811.4 | | 1055.0 | | 0.342 |
Thinning April 2017 | 39.6 | | 41.3 | | 38.0 | | 41.2 | | 0.978 |
Pruning Leaf June 2017 | 968.6 | ab z | 854.9 | b | 1149.7 | a | 1054.6 | ab | 0.028 |
Pruning Stem June 2017 | 798.8 | ab | 725.8 | b | 965.8 | a | 894.9 | ab | 0.026 |
Harvesting July 2017 | 1778.3 | | 1616.1 | | 1642.7 | | 2017.3 | | 0.179 |
Defoliation October 2017 | 2070.4 | | 2003.2 | | 2355.0 | | 2204.7 | | 0.124 |
Pruning February 2018 | 3169.4 | ab | 2761.9 | b | 3901.7 | a | 3400.5 | ab | 0.007 |
Pruning Leaf June 2018 | 3766.1 | | 3159.9 | | 3944.2 | | 3425.1 | | 0.326 |
Pruning Stem June 2018 | 3138.3 | ab | 2523.7 | b | 3650.7 | a | 2805.6 | ab | 0.038 |
Harvesting July 2018 | 1829.7 | | 2276.7 | | 1929.3 | | 2014.4 | | 0.752 |
Defoliation November 2018 | 3622.9 | | 3557.6 | | 3606.6 | | 3639.2 | | 0.986 |
Total | 23,769.9 | | 22,304.9 | | 25,601.0 | | 24,563.0 | | 0.121 |
| N Concentration (% DW) | P Value |
| 25% | 50% | 100% | 200% |
Pruning Leaf July 2016 | 3.29 | b | 3.46 | ab | 3.43 | ab | 3.59 | a | 0.013 |
Pruning Stem July 2016 | 0.96 | | 0.99 | | 0.93 | | 0.97 | | 0.891 |
Defoliation October 2016 | 2.92 | | 2.96 | | 2.95 | | 2.99 | | 0.808 |
Pruning February 2017 | 1.33 | | 1.29 | | 1.37 | | 1.36 | | 0.369 |
Thinning April 2017 | 2.78 | | 2.92 | | 2.82 | | 3.05 | | 0.201 |
Pruning Leaf June 2017 | 3.97 | | 3.98 | | 3.93 | | 4.00 | | 0.662 |
Pruning Stem June 2017 | 1.11 | | 1.11 | | 1.09 | | 1.07 | | 0.709 |
Harvesting July 2017 | 1.41 | a | 1.30 | b | 1.44 | a | 1.35 | ab | 0.001 |
Defoliation October 2017 | 3.43 | | 3.51 | | 3.43 | | 3.52 | | 0.335 |
Pruning February 2018 | 2.11 | | 2.08 | | 2.12 | | 2.07 | | 0.807 |
Pruning Leaf June 2018 | 3.95 | | 3.89 | | 3.97 | | 3.94 | | 0.808 |
Pruning Stem June 2018 | 1.08 | | 1.06 | | 1.08 | | 1.09 | | 0.697 |
Harvesting July 2018 | 1.16 | | 1.14 | | 1.24 | | 1.16 | | 0.262 |
Defoliation November 2018 | 2.89 | | 2.96 | | 2.88 | | 2.95 | | 0.646 |
Table 5.
Dry weight (DW) and N concentration in the different removal events for irrigated vs. non-irrigated for trees of “Julyprince” peaches in 2016, 2017, and 2018.
Table 5.
Dry weight (DW) and N concentration in the different removal events for irrigated vs. non-irrigated for trees of “Julyprince” peaches in 2016, 2017, and 2018.
Removal Event | Dry Weight (g/tree) | P Value |
---|
Irrigated | Non-Irrigated |
---|
Pruning Leaf July 2016 | 428.3 | a z | 291.6 | b | <0.001 |
Pruning Stem July 2016 | 323.2 | a | 219.0 | b | <0.001 |
Defoliation October 2016 | 1502.3 | a | 796.0 | b | <0.001 |
Pruning February 2017 | 1350.0 | a | 517.0 | b | <0.001 |
Thinning April 2017 | 42.4 | | 37.6 | | 0.441 |
Pruning Leaf June 2017 | 1274.5 | a | 739.5 | b | <0.001 |
Pruning Stem June 2017 | 1070.1 | a | 622.6 | b | <0.001 |
Harvesting July 2017 | 1870.3 | | 1656.9 | | 0.136 |
Defoliation October 2017 | 2258.2 | | 2058.4 | | 0.074 |
Pruning February 2018 | 3709.4 | a | 2907.4 | b | <0.001 |
Pruning Leaf June 2018 | 4067.6 | a | 3080.1 | b | 0.004 |
Pruning Stem June 2018 | 3404.3 | a | 2654.9 | b | 0.010 |
Harvesting July 2018 | 2119.9 | | 1905.2 | | 0.481 |
Defoliation November 2018 | 3818.7 | a | 3394.4 | b | 0.011 |
Total | 27,239.1 | a | 20,880.4 | b | <0.001 |
| N Concentration (% DW) | P Value |
| Irrigated | Non-Irrigated |
Pruning Leaf July 2016 | 3.45 | | 3.43 | | 0.695 |
Pruning Stem July 2016 | 0.98 | | 0.94 | | 0.452 |
Defoliation October 2016 | 2.98 | | 2.93 | | 0.365 |
Pruning February 2017 | 1.32 | | 1.35 | | 0.384 |
Thinning April 2017 | 2.94 | | 2.85 | | 0.351 |
Pruning Leaf June 2017 | 3.93 | | 4.00 | | 0.098 |
Pruning Stem June 2017 | 1.09 | | 1.11 | | 0.420 |
Harvesting July 2017 | 1.38 | | 1.37 | | 0.507 |
Defoliation October 2017 | 3.46 | | 3.48 | | 0.600 |
Pruning February 2018 | 2.08 | | 2.11 | | 0.600 |
Pruning Leaf June 2018 | 3.88 | b | 3.99 | a | 0.034 |
Pruning Stem June 2018 | 1.05 | b | 1.11 | a | 0.014 |
Harvesting July 2018 | 1.14 | b | 1.21 | a | 0.043 |
Defoliation November 2018 | 2.96 | | 2.87 | | 0.081 |
Table 6.
Dry weight (DW) and N concentration in the different removal events for drip- vs. micro-sprinkler-irrigated for trees of “Julyprince” peaches in 2016, 2017, and 2018.
Table 6.
Dry weight (DW) and N concentration in the different removal events for drip- vs. micro-sprinkler-irrigated for trees of “Julyprince” peaches in 2016, 2017, and 2018.
Removal Event | Dry Weight (g/tree) | P Value |
---|
Drip | Micro-Sprinkler |
---|
Pruning Leaf July 2016 | 486.7 | | 369.9 | | 0.135 |
Pruning Stem July 2016 | 365.7 | | 280.6 | | 0.153 |
Defoliation October 2016 | 1716.1 | | 1288.6 | | 0.086 |
Pruning February 2017 | 1505.8 | | 1194.2 | | 0.392 |
Thinning April 2017 | 53.3 | a z | 31.5 | b | 0.028 |
Pruning Leaf June 2017 | 1272.2 | | 1276.7 | | 0.973 |
Pruning Stem June 2017 | 1058.4 | | 1081.7 | | 0.825 |
Harvesting July 2017 | 2076.6 | | 1663.9 | | 0.087 |
Defoliation October 2017 | 2315.0 | | 2201.5 | | 0.432 |
Pruning February 2018 | 3962.9 | | 3455.8 | | 0.116 |
Pruning Leaf June 2018 | 4674.7 | a | 3460.6 | b | 0.019 |
Pruning Stem June 2018 | 4074.4 | a | 2734.2 | b | 0.004 |
Harvesting July 2018 | 1586.4 | b | 2653.3 | a | 0.036 |
Defoliation November 2018 | 3933.0 | | 3704.5 | | 0.360 |
Total | 29,081.2 | a | 25,397.0 | b | 0.015 |
| N Concentration (% DW) | P Value |
| Drip | Micro-Sprinkler |
Pruning Leaf July 2016 | 3.53 | | 3.38 | | 0.190 |
Pruning Stem July 2016 | 0.99 | | 0.98 | | 0.929 |
Defoliation October 2016 | 3.16 | a | 2.80 | b | 0.016 |
Pruning February 2017 | 1.28 | | 1.37 | | 0.072 |
Thinning April 2017 | 2.93 | | 2.95 | | 0.912 |
Pruning Leaf June 2017 | 3.93 | | 3.94 | | 0.922 |
Pruning Stem June 2017 | 1.09 | | 1.08 | | 0.752 |
Harvesting July 2017 | 1.45 | | 1.32 | | 0.109 |
Defoliation October 2017 | 3.48 | | 3.43 | | 0.484 |
Pruning February 2018 | 2.11 | | 2.05 | | 0.587 |
Pruning Leaf June 2018 | 3.92 | | 3.83 | | 0.410 |
Pruning Stem June 2018 | 1.16 | a | 0.94 | b | 0.009 |
Harvesting July 2018 | 1.15 | | 1.13 | | 0.611 |
Defoliation November 2018 | 3.09 | a | 2.84 | b | 0.002 |