California Pepper Commission


Proposal Baameur Utilization Uptake Data to Refine Nitrogen Management Tool for Peppers

Utilization of Nitrogen Uptake Data to Refine Nitrogen Management Tool for Peppers

Aziz Baameur, Farm Advisor, UCCE Santa Clara County.
Richard Smith, Farm Advisor, UCCE Monterey County

Aziz Baameur
UC Cooperative Extension, Santa Clara County. 1553 Berger Dr., Bldg. 1
San Jose, CA 95112
Phone/Fax: (408) 282-3127 / (408) 298-5160

Introduction and Rationale

The Agricultural Order issued by the Central Coast Regional Water Quality Control Board (CCRWQCB - which spans from Santa Barbara to Santa Cruz Counties) in March of 2012 required growers to monitor and implement practices to reduce nitrate-nitrogen (NO3-N) losses to surface and ground water. As written, all operations that produce over 1000 acres and that produce 'high risk' crops such as peppers, and that use chlorpyrifos or diazinon are placed into Tier 3 compliance category which has specified regulations concerning the movement of nitrates to surface and ground waters. The new regulations require growers to implement a certified Irrigation and Nutrient Management Plan (INMP) to document information on nitrogen applied to crops vs nitrogen removed by crops. This information would be used to calculate a nitrogen balance ratio and growers are given three years to demonstrate nitrogen balance ratios of 1.2 for crops that are grown in an annual rotation. This aspect of the regulations is currently stayed by court order, but it is clear that regulations will soon be enacted that will require growers to implement and document improvements in nitrogen use efficiency. Given current production practices and traditional fertilization programs, these new restrictions would be difficult for many growers to comply with. Clearly, given this new regulatory environment it is critical that the pepper industry develop and refine data on nitrogen uptake to establish reasonable guidelines on nitrogen use by peppers.

CropManage is a web-based software program for managing nitrogen and water in lettuce and other crops. It was developed by Michael Cahn, UCCE Monterey County and is maintained on the on a server at UC, Davis. It was designed to be an intuitive tool for growers and farm managers to use. Growers can utilize this tool manage nitrogen and irrigation applications on a block by block basis on their ranches. The web application uses a secure login procedure so only individuals that the growers grant permission can gain access to the ranch information. CropManage is a key tool for addressing the Agricultural Order issued by the CCRWQCB. Crop Manage can be applied to pepper, but we need to develop good nitrogen uptake curves. Studies funded by the California Pepper Commission in 2011 indicated that bells and jalapenos pepper take up about 240 lbs N/A. This is important data, however, we need to have more data points during the crop cycle to effectively incorporate peppers into the CropManage program.


The main goals of this field study are:
To refine total N uptake of bell peppers and utilize this information to develop a crop growth model that models nitrogen uptake by peppers over the crop cycle that can be utilized by the CropManage program.
To evaluate the N application to N uptake ratio. Four biomass samples will be collected over the season from which we can develop a nitrogen uptake curve for peppers. This information will facilitate adding peppers to the CropManage web based nitrogen and irrigation management program ( This program is a key tool for growers to guide them in nitrogen fertilization and irrigation management.


Materials and methods

The 2011 N uptake research funded by the CPC indicated that bell and jalapeno peppers took up similar amounts of nitrogen. As a result, we will focus this research just on bell peppers. We will collect whole plant biomass samples 4-5 times over the course of the growth cycle from 8 bell pepper fields from diverse fields in Santa Clara and San Benito Counties.

From each field, three samples consisting of 4 average healthy plants will be selected.

Mature fruit will be separated from plant top shoots. Samples will be chopped to smaller pieces and dried. Each sample will be ground and homogenized and a representative sample will be sent to UC ANR diagnostic laboratory for total N determination. After the "main" harvest, samples will be analyzed for the three major elements NPK.

At each plant sampling, we will take a composite soil (0-12") from each field. Soil samples will be dried, ground and submitted for N analyses.

We will also collect yield data from cooperating growers to correlate yield levels with collected N data. The end product would be a range of N requirements for differing crops and yield levels that growers would use as guidelines for N application and uptake.

Time line

March/April 2013 Contacting cooperating growers
May-June 2013 Selecting fields and marking plant plots
July-October 2013 Collecting samples
Preparing samples
November-December 2013 Submitting samples to ANR lab Data analysis
Data tabulation preparation of report

Proposed Budget

Activity / item Cost Total
Labor  $5,500
Lab analyses: 200 samples $17.5/sample $3,500
Travel to and from sites  $2,000
Supplies: bags, clippers, flags, tape, etc  $500
Total  $11,500

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