Progress 01/04/10 to 12/31/12
Outputs
Progress Report Objectives (from AD-416): Determine real time seasonal nitrogen requirements to improve FUE of young and maturing pomegranates using drip and subsurface drip irrigation. Determine required level of nitrogen to maintain N levels in maturing pomegranates. Determine effect of N fertilization on macronutrient concentrations. Approach (from AD-416): The project will use a complete randomized design of 2 irrigation treatments and 3 fertilization treatments with 5 replications. The water requirement will be determined by weighing lysimeter and the fertilization will be determined by tissue sampling in years 2 and 3 of the project. This is a field project on 2 acres. Documents Reimbursable with CDFA. Log 40504. This project supports research under objective 2 of the in-house project, Developing sustainable water management strategies. Nutrition and irrigation are critical components of sustainable management. This research quantifies the nitrogen requirements for pomegranate. Pomegranate is a minor crop that has attracted much interest because of its presumed nutritive qualities. It is assumed to be both drought and salt tolerant. However, there are very little data on the water and fertilizer requirements of a developing pomegranate orchard as well as a developed crop. This research was designed to provide data that will characterize the water and fertilizer requirements of pomegranate. This report covers the first 3 years of the project. The pomegranates were planted in April 2010 and were provided uniform applications of water and nitrogen fertilizer to insure uniform plant establishment. The trees were irrigated using surface and subsurface drip irrigation. The fertilizer treatments were to be 50%, 100% and 150% of required nitrogen. The experimental design was a randomized complete block with 5 replications. The field had previously been cropped with wheat to insure a uniform level of nitrogen in the soil, so to not confound the results. The trees were pruned to develop as a shrub. The initial results from the 2011 nitrogen sampling of plant tissues indicated that pomegranate was very responsive to ammonium nitrate fertilizer. Additional studies with suction cup samplers demonstrated that there was very little percolation loss resulting from either the high frequency surface or subsurface drip irrigation. The use of high frequency drip irrigation/fertigation method minimizes soil water saturation that causes soil anaerobic conditions and leaching losses of NO3-N - Nitrate-Nitrogen. The first year of differential fertilizer treatments was 2012. It also was the first year for automatic control of the irrigation system using the weighing lysimeter. The evapotranspiration in 2012 was 462 mm; and 456 mm of water was applied by the subsurface drip system and 441 by the surface drip system. The maximum crop coefficient was approximately 0.5. The nitrogen application was approximately 50, 150 and 250 lbs/acre for the 50%, 100% and 150% treatments. These values were too high and will be modified in the future. Analysis of the soil nitrate levels demonstrated very little movement below the root zone. This was a result of the high frequency irrigation being used in this field. Irrigation was initiated when 1 mm of water loss was recorded by the weighing lysimeter being used to control the irrigation and determine crop water use. The total yield of prime and juice fruit was 18.7 tons/acre for the surface drip and 20.6 tons/acre for the subsurface drip. These are values that are comparable to commercial yields. Nitrous oxide emissions were monitored during irrigation using above ground flux chambers in 2012. The data show that emissions significantly increased as the nitrogen concentration increased in the irrigation water. However, emissions were significantly reduced for all concentrations of injected nitrogen for subsurface drip compared to surface drip irrigation. Images of the tree canopy taken with a multi- spectral camera were used to determine if irrigation affected plant size. The data indicated that trees irrigated with subsurface drip irrigation were larger than trees irrigated with surface drip irrigation. The results from the first 3 years of the study demonstrate that pomegranate will respond to nitrogen fertilizer but additional work is needed to refine the required nutrient levels. The surprising result was the effect of surface drip irrigation (DI) vs subsurface drip irrigation (SDI). There appeared to be positive treatment effects associated with subsurface drip irrigation as compared to surface drip. There were slightly larger yields and larger trees with SDI compared to DI. Additionally, there were significantly reduced nitrous oxide emissions with SDI compared to DI. Nitrous oxide is a significant contributor to global warming and the ability to control losses with the irrigation system is an important finding. Anecdotal evidence demonstrated lower weed population with SDI than DI which will have positive impacts on water supply, labor and chemical usage. All will be reduced as result of the use of SDI. These results have provided the first data for crop water use for a developing pomegranate orchard.
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Progress 10/01/11 to 09/30/12
Outputs
Progress Report Objectives (from AD-416): Determine real time seasonal nitrogen requirements to improve FUE of young and maturing pomegranates using drip and subsurface drip irrigation. Determine required level of nitrogen to maintain N levels in maturing pomegranates. Determine effect of N fertilization on macronutrient concentrations. Approach (from AD-416): The project will use a complete randomized design of 2 irrigation treatments and 3 fertilization treatments with 5 replications. The water requirement will be determined by weighing lysimeter and the fertilization will be determined by tissue sampling in years 2 and 3 of the project. This is a field project on 2 acres. This project supports objective 1 of the parent project. In response to water shortages and rising water and energy costs, California, growers are changing their irrigation practices from flood and furrow irrigation to sprinkler and drip irrigation. However, many growers are still using conventional fertilizer methods such as: soil incorporating and banding methods that apply most fertilizers early in the season when crops need it the least. These fertilizer application methods are not efficient and/or well suited for DI and SDI irrigation methods. This is a report on the activities of the second year of the project. We completed the installation of orchard and control system installation. Baseline soil sampling, water used and applied, evapotranspiration, and basic plant measurements were made. Plant response to fertigation was confirmed and irrigation system operation was confirmed. Trees were irrigated individually with respective water treatment under micro-plot field conditions in Parlier, CA, based in part by weather data collected from CIMIS. The initial results from our nitrogen sampling of plant tissues indicate that pomegranate is very responsive to nitrogen fertilizer. The initial results from the nitrate analysis in the soils demonstrated that we have reasonably uniform nitrogen levels that will not impact the results of the study. The water balance studies demonstrated that the lysimeter system is working very well and will provide adequate data for characterizing the crop water use during the season. A late-season study that characterized the shaded area under the crop demonstrated that the subsurface drip irrigated trees had a larger canopy than the surface drip irrigated trees. Fruits were taken from the trees and discarded to prevent damage to the trees. Next year data will be collected on fruit numbers and size in response to the fertilizer treatments.
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Progress 10/01/10 to 09/30/11
Outputs
Progress Report Objectives (from AD-416) Determine real time seasonal nitrogen requirements to improve FUE of young and maturing pomegranates using drip and subsurface drip irrigation. Determine required level of nitrogen to maintain N levels in maturing pomegranates. Determine effect of N fertilization on macronutrient concentrations. Approach (from AD-416) The project will use a complete randomized design of 2 irrigation treatments and 3 fertilization treatments with 5 replications. The water requirement will be determined by weighing lysimeter and the fertilization will be determined by tissue sampling in years 2 and 3 of the project. This is a field project on 2 acres. This agreement supports Objective 1 of the parent project. The pomegranate trees were manually irrigated twice weekly using a water tank throughout the summer because the irrigation system was under construction. The acid and fertilizer tanks were installed during the winter. The control system has been prepared and was installed during the winter. The irrigation was terminated in September to harden off the plants for winter. Trunk diameters were measured in November. Soil sampling was conducted to establish a baseline for the initial nitrate nitrogen content of the soil and analysis has been completed. Average water use on the lysimeter tree was approximately 0.025 inches per day (. 6 mm/day) with a cumulative water use in the lysimeter over the season of approximately 4.5 inches (114 mm) of water. Trunk circumference results show no significant difference on plots with the main effects of irrigation systems. However, there is some difference due to blocking. This means that the trees are uniform throughout the field so there will not be differences in the treatments prior to beginning the fertilization. The installation of the instrumentation was completed in Spring 2011, and automated operation based on measured water loss by the lysimeter was begun. The fertilization treatments will be uniform across all treatments and plots in 2011. This is to insure uniform development of the trees. Differential fertilization will begin in the next growing season.
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Progress 10/01/09 to 09/30/10
Outputs
Progress Report Objectives (from AD-416) Determine real time seasonal nitrogen requirements to improve FUE of young and maturing pomegranates using drip and subsurface drip irrigation. Determine required level of nitrogen to maintain N levels in maturing pomegranates. Determine effect of N fertilization on macronutrient concentrations. Approach (from AD-416) The project will use a complete randomized design of 2 irrigation treatments and 3 fertilization treatments with 5 replications. The water requirement will be determined by weighing lysimeter and the fertilization will be determined by tissue sampling in years 2 and 3 of the project. This is a field project on 2 acres. Documents Reimbursable with CDFA. Log 40504. This agreement was established in support of Objective # 1 (Determine new water requirements and develop improved management practices and systems for irrigated crops to promote efficient resource use and water quality protection) of the in-house project and the goal was to determine the water requirements of horticultural crops grown in arid and semi-arid areas. The pomegranate trees were donated by Paramount Farms and the planting was completed in April 2010. The subsurface drip tubing was installed on the field site located on the Kearney Agricultural Center along with the filter set for the drip system. The remaining materials have been ordered to complete the installation of the surface and subsurface drip irrigation. The trees are being irrigated manually while the drip system installation is completed.
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