Almond Nitrogen Nutrition

Transcription

1 Almond Nitrogen Nutrition using the Internet Based Fertilization Program PATRICK H. BROWN STEVE A. WEINBAUM FARBOD YOUSSEFI Pomology Department University of California-Davis

2 First Principles: QuickTime and a TIFF (LZW) decompressor are needed to see this picture.

3 1. Nitrogen Demand and Fertilizer Response is Determined by Environment For all nutrients the environment in which the tree is growing must be considered. Here the performance of Pistachio in the swale is much worse then the performance in on the ridges. This may be the result of changing soil conditions that limit the availability of a nutrient. For the micronutrients (Mn, Cu, Fe, Zn,B) this might imply that special measures are needed to correct the deficienc in the poor producing parts of the orchard. Soil and plant sampling should be performed. For the macronutrients (N, K, S) it is unusual for soil type to dramatically alter the availability of these nutrients hence it is unlikely that the poor performance is a result of a macronutrient deficiency.

4 2. Nitrogen Demand is Driven by Yield and New Growth. For the macronutrients, N, K, Ca, P, S, Mg yield is the most important determinant to nutrient demand. This demand occurs both at a whole field level (total yield) and may also occur locally at the branch level as indicated by the nutrient deficiencies surrounding this large cluster of Pistachio nuts.

5 Plant Nutrition Principles 3. Nutrients are obtained by living, active roots and growing plants Requires water for uptake No uptake during dormancy Highly regulated uptake (in Almond uptake will not exceed demand) 4. There is an optimal tissue nutrient concentration above which no benefit occurs. Critical Value.

6 Pistachio K 3500 Critical Value1.7% Nut Yield (lbs/acre) r 2 =0.48 Madera July-August Leaf K Concentration (%) Nutrients added beyond that needed for maximal yield (1.7% in this example), does not significantly improve yield and may result in nutrient imbalance or excess disease.

7 Optimizing Fertilization of Trees Ensuring nutrients are present in an available form at the appropriate time, and in the correct amount. Determine tree nutrient demand. Growth and Cropping Replace what is removed by the crop. Time applications to match uptake. Consider all inputs. Result: Economical and environmentally sensible fertilization.

8 Tree Nutrient Demand Two components of demand Total Nutrient Demand (Yield, Growth, Storage) Seasonal Patterns of Demand and Uptake Experimental Methods Sequential branch and whole tree harvest, partitioning and nutrient analysis (excavate 5 mature trees each three months for 15 month period. 25 trees) 15 N, and 10 B labeling References: Brown et al, Rosecrance et al, Weinbaum et al.

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10 Total Removal (g/tree) Annual Distribution of Macronutrients: Pistachio Fruit + Leaves Leaves Yielding Leaves No yield N P K Ca Mg

11 When During the Year are Nutrients Required by the Tree? and When During the Year are Nutrients Acquired from the Soil?

12 Whole Tree N Contents by Organ in Almond N contents (g) Uptake 2/20 3/20 5/20 8/29 9/29 Excavation Date H ar v e st roots trunk canopy leaves fruit The amount of Nitrogen acquired by a tree, the source of the nutrient (uptake or remobilization), and the time at which that uptake occurred can be determined by conducting sequential whole tree excavations and partitioning.

13 Nutrient Fluxes (N) in Almond Stored Nutrients Total Nutrient Demand Current Year Uptake Nutrient demand Stored Nitrogen 50 Current year uptake 0 January April May July October January

14 Three Principles: When Should Nitrogen Be Applied? Uptake is driven by demand Decreased by stored nitrogen/nitrogen status Increased by Growth/Yield Uptake requires active trees and active roots Nutrients must be soluble and at the root surface at time of demand.

15 Information Required to Make Sound Fertilizer Decisions Knowledge of tree demand Knowledge of tree uptake patterns Consideration of tree N status Consideration of N Inputs N in Irrigation water N in Cover crops, amendments etc. Consideration of Environment Consideration of Application Efficiency

16 Computer Based N Management Program To assist advisors and growers in their management of Nitrogen we developed an: Interactive Web Program Integrates experimentally derived information on demand, timing, organic inputs, irrigation water nitrate and fertilization method to provide a recommended fertilization scheme. The model appears on the University of California - Davis Fruits and Nuts web site at Then select Fruits and Nuts, then the crop of interest then Production Management and finally Nitrogen Fertilization Model. Models have been constructed for Almond (N), Pistachio (N,K), Walnut (N,K) and Avocado (N,K in preparation)

17 Summary Determination of demand and uptake is critical for the optimization of fertilizer use The intricacies and site specific differences in tree production require an easy to use grower based product The construction of the model highlights information gaps (N use efficiency) and assists in management decisions (cover crop incorporation etc). Increases grower knowledge.

18 Limitations of a Budget Approach to Fertilization Site specific Need to consider soil characteristics in determining timing - grower knowledge. Requires more information than traditional approaches Best when used consistently

19 Yield and N demand is not uniform within a field. Optimal N management will require a more precise knowledge of yield variability across the field. Estimated Nitrogen Demand Lb/acre equivalent Acre plot. Yield of all 12,200 trees measured and N demand calculated: c

20 Nitrogen Demand by 5 acre Plot 340 lbs 175 lbs 125 lbs 50 lbs 250 lbs 225 lbs 100 lbs 100 lbs 225 lbs 175 lbs 75 lbs 50 lbs 280 lbs 200 lbs 50 lbs 50 lbs Pistachio Yield Whole Field Average N demand = 150 lbs N

21 Benefits of the Budget Approach Site specific management, precision management Greater sustainability Greater physiological relevance With optimal software it is easy More efficient and proactive than tissue sampling

22 Fertilization of Trees Goal: Ensure nitrogen is present in an available form at the appropriate time, and in the correct amount. Provide economical and environmentally sensible fertilization.

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