Pepper N Uptake: 1st Year study Report.
Aziz Baameur1 & Richard Smith2—Farm Advisor Santa Clara1 & Monterey2 Counties.
The purpose of this project is to provide growers with basic information on the uptake of nitrogen, potassium and phosphorus by peppers to provide guidelines for fertilizing pepper crops. The main objective is to provide pepper growers with necessary information to successfully grow pepper crops and remain within the environmental requirements as described in the water quality regulations.
The main goal of this field study is to determine the total N uptake of the two dominant pepper crop typesóbells and chili as represented by jalapeños.
Typically, growers apply between 200-300 lbs of N or more per acre. How much of the N ends up in the fruit and how much in the plant? Estimates are between the 160 to 200 lbs. taken by the plant about 60 lbs on average end up in the p fruit.
This project evaluated four jalapeño (J1 to J4) and four bell (B, B2, B3, and B5) pepper fields. Table 1 shows field codes, location, and row configuration. See Appendix A for field and variety information.
In each field we designated plots that were five plants, single row system, or 10 plants in double row configuration. We selected the first plot (replicate 1) 100 ft down the row from the edge of the field. The second replicate was set eight beds over and 200 ft down from the edge of the field. The third and four replicates followed the same pattern and were placed 300 and 400 ft down the field.
We harvested each field twice; field B3 that was harvested once only. We counted the harvested fruit, sorted it into economical and cull categories and weighed each category. From each plot, we sampled 15-20 peppers were evaluated for fresh and dry weight and nutrient content. We submitted dried samples to the UCD analytical laboratory for NPK analysis.
At the second harvest, in addition to the fruit harvest and sampling, we harvest whole aboveground plant parts in each plot, weighed them, sub-sampled them, dried and submitted the sub-sample to UCD analytical laboratory.
Following harvest, we took two soil samples from the 0-12 and 13-24 inch depths from each plot. Samples were air dried, ground, and submitted for Total NPK analyses to UCD laboratory.
Yield and Dry Matter.
Estimated average plot production of jalapeño fruit was 32 tons per acre. Plot yield ranged from low 24 to a high 40 tons per acre. Plant productivity ranged from 3.7 to 5.9 lbs/plant per plot. Fruit size as expressed in grams per fruit averaged 22.8 g (0.8 oz) and ranged from 21 (0.7 oz) to 24 grams (0.85 oz) per fruit.
Bell pepper plots displayed similar trends. Plot production was higher than jalapeño where average fruit plot yield was 43 tons/acre. Yield ranged from 34 tons and 56 tons. Plant production was similar to that of jalapeño, 4.9 lbs/plant. And as expected, fruit size averaged 196 grams (6.9 oz, but ranged from 156 g (5.5 oz) to 219 g (7.7 oz) each.
Estimate dry matter (DM) was about equally same in both types of fruit. In both cases, fruit DM accumulation was higher than in plants (Table 1).
Table 1. Average Pepper Fruit Yield and NPK content
Table 1 shows the nutrient uptake for N, P and K by jalapeño and bell pepper fruit per acre (Table 1). Potassium uptake was greater than N uptake in both jalapeño and bell peppers. Jalapeño took up more of each nutrient than bells.
Data show that while P uptake is lowest of three major elements, jalapeŮo fruit (139, 20, 156 #/a, respectively) had higher concentration than bell pepper fruit (111, 16, 135 #/a, respectively). Moreover, jalapeño fruit had more than twice P as compared to jalapeño plants. Bell pepper tended to equally partition P between fruit between fruit and plant.
Both nitrogen (N) and potassium (K) concentrations were higher in jalapeño fruit than in plants. Bell pepper did not show this trend, as shown in table 2. Jalapeño data also show that jalapeño fruit accumulated 56-58% of N and K and over 70% of P. Overall averages were around 50% NPK in bell pepper fruit and plants.
Table 2. Jalapeño & Bell Pepper Plant Dry Matter NPK uptake
Dry Matter Tons/A
Cumulative biomass uptake by of N was slightly higher for jalapeño (by 16 lbs/acre) than bell pepper plants (Table 3). However, cumulative P and K were similar in both. Total cumulative DM was also comparable in both of crops.
Table 3. Average Nutrient (NPK) Uptake by Bell & Jalapeño Fruit and Pepper Plant-2011
Looking at the data in different way, table 4 indicates efficiencies in nutrient uptake. Efficiency is defined here as pounds of nutrient taken to produce a unit (ton) of fruit. Data indicate that to produce one ton of jalapeño fruit the crop would require more N and K than a ton of bell pepper fruit. Jalapeños would need between 6 and 9 pounds of N (with a mean of 7.7), and between 6 and 10.5 pounds of K (averaging 8.5 lbs) to produce one ton of jalapeño pods. For one tons of bell pepper fruit, the plant would take up between 4 and 9 lbs. of N (average: 5.2) and 5 and 10 lbs. of K (average: 6.3 lbs/ton). The uptake of P is the same in both crop types, about 1 pound for each ton of pepper and would range between .6 and 1.3 lbs of P for each ton of fruit.
Table 4. Ratio of NPK to ton of production
End of season soil pH in all fields averaged 7.4 in the top 24 inches. There was more residual P (63%) in the upper 12 inches than in the lower foot. Similarly, K concentration in 0-12 inches was about 35% higher as compared to the underlying 12 inches. However, organic matter (OM) presence was slightly higher, 25% more, in the 0-12" than in the 12-24" layer.
Total residual N average in all fields was estimated to be 89 lbs/acre. Soil P estimates reached around 50 lbs/acre, and soil K was around 144 lbs/acre. There was not a big difference between fields of both types of pepper. As temperatures go down, the rate of mineralization is expected to decrease.
When comparing inputs to outputs (uptake), it appears that over 70% of N almost 100% of K applied were taken by pepper aboveground parts, fruit and plant biomass. However, the phosphorus was 52% partitioned between fruit and plant.
Table 5. Average analyses of soil samples sites at the 0-1 and 1-2 foot soil depth-1 and 1-2 foot soil depths
From this study we concluded:
- Nitrogen and potassium uptake was several folds higher than phosphorus uptake by plant and fruit of jalapeño and bell pepper.
- Jalapeño fruit tended to accumulate more N and K (139 and 150 lbs. respectively) at the expense of the plant.
- Bell pepper plant equally partitioned N and K between leaves, stem and fruit (110 and 135 lbs. each).
- Both types of pepper had similar of dry matter produced.
- For each ton of jalapeño fruit produced, 8 lbs. of N and 9 of K were taken into the canopy and fruit portions.
- For each ton of bell pepper fruit produced, 5 lbs. of N and 6 of K were taken up by above ground biomass.
- Both pepper types used the same amount of P to produce 1 tons of fruit.
- Based on soil analysis of the production field included in this study, there were comparable amounts of N, P, and K left in the soil at the end of the production season by each pepper crop.
- Of the total nutrients supplied by growers, 70% of N and 100% of K made their way into fruit and plant canopy. Less than half of the P added was taken up by the crop.
More field studies are needed to shed light on these interactions.
We would like to acknowledge the financial support of the California Pepper Commission.
We are grateful to the participating growers for their contributions and support during this project.
Appendix 1. Pepper Field location, varieties, bed configuration and plant sample size
Pepper Field location, varieties, bed configuration and plant sample size
Plants per Plot
Bell Pepper Fields
Plants per Plot
12" X 12"
12" X 12"
12" X 12"
12" X 11"
Appendix 2. Graphic Presentation of Fruit and plant nutrient Uptake.
Appendix 3. Aggregate NPK inputs by crop.