Department of Chemical and Biological Engineering, Ames, IA BioMaP REU Program

July 2012

Jerson Valenzuela, Bernardo del Campo, Robert C. Brown

Acknowledgements: This material is based upon work supported by the National Science Foundation under Grant No. EEC 0851519.

Lettuce Response to Biochar and Fertilizer

Introduction Biochar is a co-product of thermochemical conversion of biomass.

Studies have demonstrated its ability to reduce greenhouse gas

emissions by sequestering carbon and improve soil characteristics

such as water retention, pH CEC, etc. A test was conducted to

observe the effects of 2 different biochar soil mixtures on plant

growth.

Results

Some problems were encountered when starting this experiment. Volume

from the premixed samples of soil (Control) were lost from water added to

collect leachate, so sand was added to even the volume out. To prevent this

from happening on the non-premixed samples, we placed paper towel

underneath so there would be no loss of sample. Also, the plants which

were growing from the samples with fertilizer, in both the premixed and

non-premixed samples, died. Germinated seeds were added to observe their

growth, but were excluded from the collected measurements.

Conclusion

• Adding biochar to soil changes the chemical and physical properties of

the soil.

• High amendment rates could dramatically impact the pH level of the

soil and the availability of nutrients, special attention should be paid to

processing conditions and types of biochar applied. Premixed biochar

and soil look necessary for stabilization of the soil and better growth.

• 50% of biochar for this type of soil seemed too much. It increased pH

levels higher than they were desired. Smaller additions and longer

mixing times are strongly recommended

Methodology

Treatments were split in:

Soil only and Red Oak and Corn Stover Biochar mix (50% by weight).

Half of the plots were prepared, one week before planting and the other half

were prepared on the day of planting.

Half of those plots were fertilized with 1g of fertilizer (15-15-15) [Photo 2.]

Each combination of Biochar x preparation and Fertilization rate were done

in triplicates (appropriately randomized)

Water was applied Monday and Friday with 20 mL of water.

Leachate was collected at the beginning and at the end and the pH was

measured.

Objectives

• Study the differences between

plant growth in premixed soils,

and non-premixed soils with

biochar.

• Observe the differences in soil

properties

Ph

oto

2:

Tak

en b

y J

erso

n

Ph

oto

3:

Tak

en b

y J

erso

n

Sample pH BpH

Control (Soil) 7.80 7.50

Soil + R.O. B.C. 50% 9.05 7.85

Soil + C.S. B.C. 50% 8.29 7.65

Table 1 shows the pH balance

of the soils prior to use. Note

the high levels of pH in the two

samples mixed with biochar.

Treatment C (%) N (%) OM (%)

BCRF Soil 3.5 0.1 6.5

Soil + R.O. BC 12.9 0.2 23.2

Soil + C.S. BC 13.5 0.3 24.2

Treatment NO3-N P Mehlich 3 K Mehlich 3

BCRF Soil 19 32 193

Soil + R.O. BC 8 15 210

Soil + C.S. BC 1 110 2621

Treatment N (%) NO3-N NH4-N

BCRF Soil 0.1 19.0 9.0

Soil + R.O. BC 0.2 8.0 1.0

Soil + C.S. BC 0.3 1.0 BDL

Tab

le 4

Tab

le 2

Tab

le 3

Table 2 shows the percentage of

Carbon, Nitrogen, and Organic

Matter the samples hold. Note the

increased amount of Carbon and

Organic Matter.

Table 3 shows the percentage

of NPK nutrients without

fertilizer.

Table 4 shows the

percentage of Nitrogen

within the samples.

Chart 1 shows the

pH levels from the

leachate collected

from each sample.

Note that in the

premixed samples,

the leachate

collected contained

more soil than that

of the non-

premixed.

Chart 2 shows the average heights of both the premixed and non-

premixed samples without fertilizer. Referring to the previous tables

shown, high pH levels can be found in the soils with biochar. The

Control samples were the soil samples, and had a small pH level

[Table 1]. The nutrients shown [Table 2, Table 3, and Table 4] affect

plant growth.