Improving Nitrogen Synchronization of Local Fertilizers, Soil Fertility, and Crop Quality with Biochar Application

Final report for SW16-021

Project Type: Research and Education
Funds awarded in 2016: $259,816.00
Projected End Date: 12/31/2019
Grant Recipient: University of Hawaii at Manoa
Region: Western
State: Hawaii
Principal Investigator:
Dr. Nguyen Hue
University of Hawaii at Manoa
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Project Information

Abstract:

It is hypothesized that a combination of biochar and compost when applied to nutrient-poor soils would enhance soil fertility and plant growth more than when biochar or compost is applied separately. To test this hypothesis, a greenhouse experiment was conducted, consisting of two wood-based biochars at 0 and 2% and 2 composts (a vermi- and a thermos-compost) at 0 and 2%, factorially applied to two highly weathered, acid soils (an Oxisol and a Ultisol) of Hawaii. Two additional treatments: 2 cmolc/kg lime + 2% vermi-compost and 2 cmolc/kg lime + 2% thermo-compost were included for comparison. Chinese cabbage (Brassica rapa cv. Bonzai) was used as the test crop. Table 1 shows cabbage fresh weight and N uptake as affected by the various treatments.

Table 1. Cabbage fresh weight and N uptake as affected by biochar, compost, and lime amendments.

                                                   Leilehua Ultisol                                                 Wahiawa Oxisol

                                Shoot fresh weight          N uptake             Shoot fresh weight          N uptake

Treatment                          g/plant                 mg N/plant         g/plant                                 mg N/plant

Lactree wood                     6.0                        21.0                        16.0                                        40.0

Hilo wood                           4.9                       10.5                        17.0                                        33.0

Vermicompost                  13.5                        37.0                        17.5                                        41.0

Thermocompost              12.5                         29.0                        14.5                                        33.0

Lactree + vermi            23.0                          68.0                        17.0                                          44.0

Lactree + thermo             12.0                        29.0                        21.0                                        41.0

Hilo wood + vermi           18.0                        52.0                        16.5                                        58.0

Hilo wood + thermo         14.0                        40.0                        21.5                                        46.0

Lime + vermi                   14.5                        31.0                        23.0                                        49.0

Lime + thermo                  7.0                         27.0                        6.5                                         26.0

 
   

Our preliminary findings were: (1) the use of biochar in combination with compost improved soil fertility and increased plant growth, and (2) the effect varied with types of biochar, compost, as well as with plant nutrient studied: Lactree wood biochar + vermi-compost seemed to be the best soil amendment in terms of nutrient availability and plant growth.

Year 2.

  1. Effects of biochar on crop growth under tropical field conditions.

        Effects of biochar on crop and soil under field conditions have been lacking. Thus, a field experiment was conducted on an Oxisol (Rhodic haplustox, Wahiawa series) in Oahu Island, Hawaii. A biochar locally produced from macadamia shell feedstock was applied along with either urea, or organic nitrogen (N) fertilizers (blood meal: 10% N and Organic Farm: 12% N). Sweet corn (Zea mays), soybean (Glycine max), and okra (Abelmoschus esculentus) served as the test crops. The N application rates were 150 and 300 kg N/ha, and biochar rates were 0, 2, and 4% by weight. The experiment had a factorial design, with biochar rate as main plot, N source as subplot, and N rate as sub-subplot. There were 3 replications per treatment. Table 1 shows selected chemical properties of the soil and biochar; and Figure 1 shows the set-up of the experiment.

Table 1. Selected chemical properties of the Oxisol soil and biochar used in the field experiment.

Material

 

Total

Mehlich-3 extractable, mg/kg

 

pHł

ECł, dS/m

C, %

N, %

P

K

Ca

Mg

Fe

Mn

Zn

Oxisol soil

5.38

1.50

  1.5

0.14

    49

  600

2100

  253

 18

342

32

biochar

9.15

2.40

65

0.41

2500

7000

2120

3100

189

103

56

ł pH and EC (Electrical Conductivity) were measure in 1:1 in water for soil and 1:5 for biochar.

Our preliminary results showed that the N use efficiency markedly increased in the presence of biochar, especially for corn, okra, and even soybean (Tables 2 and 3). Interestingly, the effect of biochar on plant growth seemed to extend beyond N nutrition because the treatments receiving biochar but no N input also out-yielded those having N input but no biochar (Figure 2). Our experiment will be continued for some more years to test the prolonged/aging effect of biochar.

Table 2. The effect of biochar, N sources and rates on growth parameters of okra (Abelmoschus esculentus), soybean (Glycine max), and sweet corn (Zea mays). Different letters in each column per soil amendment (i.e., biochar, N source, N rate) indicate statistically significant difference at 95% level.

Factor

Okra

Soybean

Sweet Corn

Plant Height (cm)

Yield (g/10 plant)

Plant height (cm)

Biomass (g)

Yield

(g Pods)

Pod %

Plant height (cm)

Total Biomass (g/3 plants)

Stover

(g/3 plants)

Ears

(g/ 3 plants)

Biochar Application rate (% of soil weight)

Control

116a

1631a

68.5a

2332c

1141b

48.6a

119a

384c

247c

136c

2%

120a

1932a

69.1a

2589b

1183b

45.3b

123a

662b

350b

307b

4%

111a

1880a

71.6a

3270a

1515a

46.3ab

118a

790a

409a

381a

Fertilizer Source (Organic and Synthetic)

Control

121a

1134b

64.8b

2375b

1031b

42.5b

117a

420c

239c

171c

Blood Meal

110a

2019a

69.9ab

2665a

1279a

48.2a

119a

642ab

333b

309a

Organic Farm

109a

1998a

73.2a

2834a

1335a

47.3a

118a

615b

318b

296ab

Urea

123a

1767a

68.6ab

3869a

1350a

47.0a

125a

675a

403a

271b

N Application Rate (kg N/ha)

Control

121a

1134b

64.8b

2375b

1031b

42.5b

117a

420c

239c

171c

150

114a

1760a

68.7ab

2763a

1308a

47.3a

119a

583b

341b

241b

300

114a

2096a

72.4a

2817a

1335a

47.6a

122a

705a

362a

343a

Table 3. Analysis of Variance (ANOVA) for the studied factors and interaction under factorial in split plot design with three blocks. Numbers indicate probability of differences.

SOV

d.f.

Okra

Soybean

Sweet Corn

Plant Height

Yield

Plant height

Biomass

Yield (Pods)

Pod %

Plant height

Total Biomass

Hay

Ears

Block

2

 

 

 

 

 

 

 

 

 

 

Biochar (B)

2

0.75

0.41

0.21

0.001**

0.001**

0.003**

0.75

0.001**

0.001**

0.01*

Error (a)

4

 

 

 

 

 

 

 

 

 

 

Fertilizer (F)

3

0.25

0.03*

0.01*

0.02*

0.007**

0.001**

0.57

0.001**

0.001**

0.001**

N Rate (N)

2

0.93

0.16

0.02*

0.06

0.07

0.02*

0.42

0.001**

0.003**

0.02*

B X F

6

0.31

0.77

0.24

0.02*

0.01*

0.03*

0.56

0.02*

0.001**

0.18

B X N

4

0.81

0.87

0.95

0.34

0.51

0.67

0.93

0.07

0.18

0.25

F X N

6

0.21

0.61

0.81

0.33

0.55

0.48

0.77

0. 11

0.11

0.67

B X F X N

12

0.44

0.44

0.51

0.63

0.95

0.25

0.62

0.24

0.52

0.02*

Error (b)

21

 

 

 

 

 

 

 

 

 

 

Total

62

 

 

 

 

 

 

 

 

 

 

  1. A greenhouse experiment studying the effect of placement (surface applied vs. incorporated) of biochar + compost combination on annual and perennial crops has been established.

An Andisol (Typic hapludand, Tantalus series) and an Oxisol (Rhodic haplustox, Wahiawa series) were used, each received 4% wood-based biochar and 4% compost (volume:volume) either surface applied or mixed with the top 10-cm soil in columns having 22-cm depth and containing 1.2 L of the amended soil. Chinese cabbage (Brassica rapa, Chinensis group) and papaya (Carica papaya) served as the test crops. Preliminary results will be available in the next three months.

Project Objectives:

Figure 1. Biochar and N fertilizer experiment at the Poamoho field experiment (Oxisol soil) on Oahu, Hawaii.
Figure 2. Corn yield as affected by biochar and N fertilizer applications in a field trial on an Oxisol in Hawaii (yields were the average of two N rates: 150 and 300 kg N/ha).

Year 1. The objectives of our experiment are

(1) to examine the effect of biochar on N dynamics (i.e., potential loss and rate of mineralization) of organic fertilizers over time and

(2) to evaluate the combined effect of biochar and compost on vegetable growth.

Year 2. The objectives of our experiments are

(1) to examine the effect of biochar on N dynamics (i.e., potential loss and rate of mineralization) of organic fertilizers over time under tropical field conditions, and (2) to evaluate the placement (surface application vs. incorporation) effect of biochar + compost combination on the growth of annual and perennial crops.

 

Cooperators

Click linked name(s) to expand
  • Dr. Amjad Ahmad
  • Dr. Theodore Radovich

Research

Hypothesis:

A combination of biochar and compost when applied to highly weathered tropical soils would enhance soil quality and plant growth more than when biochar or compost is applied separately.

Materials and methods:
  1. Effects of biochar on crop growth under tropical field conditions.

        Effects of biochar on crop and soil under field conditions have been lacking. Thus, a field experiment was conducted on an Oxisol (Rhodic haplustox, Wahiawa series) in Oahu Island, Hawaii. A biochar locally produced from macadamia shell feedstock was applied along with either urea, or organic nitrogen (N) fertilizers (blood meal: 10% N and Organic Farm: 12% N). Sweet corn (Zea mays), soybean (Glycine max), and okra (Abelmoschus esculentus) served as the test crops. The N application rates were 150 and 300 kg N/ha, and biochar rates were 0, 2, and 4% by weight. The experiment had a factorial design, with biochar rate as main plot, N source as subplot, and N rate as sub-subplot. There were 3 replications per treatment. Table 1 shows selected chemical properties of the soil and biochar; and Figure 1 shows the set-up of the experiment.

Table 1. Selected chemical properties of the Oxisol soil and biochar used in the field experiment.

Material

 

Total

Mehlich-3 extractable, mg/kg

 

pHł

ECł, dS/m

C, %

N, %

P

K

Ca

Mg

Fe

Mn

Zn

Oxisol soil

5.38

1.50

  1.5

0.14

    49

  600

2100

  253

 18

342

32

biochar

9.15

2.40

65

0.41

2500

7000

2120

3100

189

103

56

ł pH and EC (Electrical Conductivity) were measure in 1:1 in water for soil and 1:5 for biochar.

  1. A greenhouse experiment studying the effect of placement (surface applied vs. incorporated) of biochar + compost combination on annual and perennial crops has been established.

An Andisol (Typic hapludand, Tantalus series) and an Oxisol (Rhodic haplustox, Wahiawa series) were used, each received 4% wood-based biochar and 4% compost (volume:volume) either surface applied or mixed with the top 10-cm soil in columns having 22-cm depth and containing 1.2 L of the amended soil. Chinese cabbage (Brassica rapa, Chinensis group) and papaya (Carica papaya) served as the test crops. Preliminary results will be available in the next three months.

Research results and discussion:

Our preliminary results showed that the N use efficiency markedly increased in the presence of biochar, especially for corn, okra, and even soybean (Tables 2 and 3). Interestingly, the effect of biochar on plant growth seemed to extend beyond N nutrition because the treatments receiving biochar but no N input also out-yielded those having N input but no biochar (Figure 2). Our experiment will be continued for some more years to test the prolonged/aging effect of biochar.

Table 2. The effect of biochar, N sources and rates on growth parameters of okra (Abelmoschus esculentus), soybean (Glycine max), and sweet corn (Zea mays). Different letters in each column per soil amendment (i.e., biochar, N source, N rate) indicate statistically significant difference at 95% level.

Factor

Okra

Soybean

Sweet Corn

Plant Height (cm)

Yield (g/10 plant)

Plant height (cm)

Biomass (g)

Yield

(g Pods)

Pod %

Plant height (cm)

Total Biomass (g/3 plants)

Stover

(g/3 plants)

Ears

(g/ 3 plants)

Biochar Application rate (% of soil weight)

Control

116a

1631a

68.5a

2332c

1141b

48.6a

119a

384c

247c

136c

2%

120a

1932a

69.1a

2589b

1183b

45.3b

123a

662b

350b

307b

4%

111a

1880a

71.6a

3270a

1515a

46.3ab

118a

790a

409a

381a

Fertilizer Source (Organic and Synthetic)

Control

121a

1134b

64.8b

2375b

1031b

42.5b

117a

420c

239c

171c

Blood Meal

110a

2019a

69.9ab

2665a

1279a

48.2a

119a

642ab

333b

309a

Organic Farm

109a

1998a

73.2a

2834a

1335a

47.3a

118a

615b

318b

296ab

Urea

123a

1767a

68.6ab

3869a

1350a

47.0a

125a

675a

403a

271b

N Application Rate (kg N/ha)

Control

121a

1134b

64.8b

2375b

1031b

42.5b

117a

420c

239c

171c

150

114a

1760a

68.7ab

2763a

1308a

47.3a

119a

583b

341b

241b

300

114a

2096a

72.4a

2817a

1335a

47.6a

122a

705a

362a

343a

Table 3. Analysis of Variance (ANOVA) for the studied factors and interaction under factorial in split plot design with three blocks. Numbers indicate probability of differences.

SOV

d.f.

Okra

Soybean

Sweet Corn

Plant Height

Yield

Plant height

Biomass

Yield (Pods)

Pod %

Plant height

Total Biomass

Hay

Ears

Block

2

 

 

 

 

 

 

 

 

 

 

Biochar (B)

2

0.75

0.41

0.21

0.001**

0.001**

0.003**

0.75

0.001**

0.001**

0.01*

Error (a)

4

 

 

 

 

 

 

 

 

 

 

Fertilizer (F)

3

0.25

0.03*

0.01*

0.02*

0.007**

0.001**

0.57

0.001**

0.001**

0.001**

N Rate (N)

2

0.93

0.16

0.02*

0.06

0.07

0.02*

0.42

0.001**

0.003**

0.02*

B X F

6

0.31

0.77

0.24

0.02*

0.01*

0.03*

0.56

0.02*

0.001**

0.18

B X N

4

0.81

0.87

0.95

0.34

0.51

0.67

0.93

0.07

0.18

0.25

F X N

6

0.21

0.61

0.81

0.33

0.55

0.48

0.77

0. 11

0.11

0.67

B X F X N

12

0.44

0.44

0.51

0.63

0.95

0.25

0.62

0.24

0.52

0.02*

Error (b)

21

 

 

 

 

 

 

 

 

 

 

Total

62

 

 

 

 

 

 

 

 

 

 

Research conclusions:

Impacts

High-N organic fertilizers could be more efficiently utilized when applied in combination with certain biochars than when applied alone. This finding/recommendation would provide organic farmers some good management tools in improving their soil fertility/quality. Further more, our work suggests that good knowledge about biochar and organic fertilizer is required in their selection for a specific usage.

Accomplishments

See summary.

This is the beginning year of the project, and the reported experiment was the first of a series of up-coming experiments. A field work with similar set-up/treatments is underway.

Year 2.

Experiments evaluating long-term effects of biochar on soil properties and crop production have been established under tropical conditions. The field trial would be continued for at least three more years. Potential uses of biochar and compost on perennial crops are being studied. A Master-degree student has been trained on research work with biochar and compost.

Final report:

  1. Objective 1. Role of biochar in conserving nitrogen (N) from organic N fertilizers.

             Since N is an essential nutrient to crop growth and yield, how to preserve N during the storage of organic N fertilizers is important to the success of sustainable and especially of organic farming. With this goal in mind, we evaluated the use of biochar to minimize N loss during storage and/or after soil application. We mixed 0, 1, 2, 4, 5, and 10% (by weight) of a macadamia-shell derived biochar (locally pyrolyzed at 400 – 450 oC) with 4 high N organic fertilizers (Blood Meal, Organic-farms, Tankage, and Sustane) then periodically monitored total N in the treatments over a 9-month storage. Our results, as illustrated in Figure 1, showed that (i) a biochar mixing range of  5 – 10% (w:w) would be quite effective in preventing N loss, and (ii) N loss, however, increased as storage time progressed (even in the presence of biochar), thus N fertilizers should be stored for as short a time as possible.

Figure 1.Percent (%) loss of total N from four organic N fertilizers containing 0, 1, 2, 5, and 10% (w:w) biochar after 1, 3, 6, and 9 months of storage.https://www.ctahr.hawaii.edu/huen/submit_docs/fig1.jpg

It appears that in the presence of biochar, microbial number and activities were enhanced, resulting in N incorporation into microbial cells and/or quick conversion from organic N into NH4 and NO3 , thus minimizing NH3 volatilization, as the following leaching experiment suggested (Figure 2). Ammonium and NO3 are, in turn, retained by micro pores and ionic functional groups on the biochar surfaces.

Figure 2.Soil pH, EC, NH4 and NO3 extracted from 3 organic N fertilizers (Tankage, Sustane, and Blood-Meal) amended with 5% biochar. Values are average of 4 incubation periods (1,3, 6 ,and 9 months).https://www.ctahr.hawaii.edu/huen/submit_docs/Fig2.jpg

  1. Objective 2. Role of biochar in improving nutrient use efficiency of crops.

          The potential of biochar for improving nutrient availability to crops grown on highly weathered, nutrient-poor soils of Hawai’i was evaluated. Two biochars at 2% (w/w) made of lac tree (Schleichera oleosa) wood and mixed wood (scrapped wood and tree trimmings) with and without vermicompost or thermocompost at 2% (w/w) were added to an Ultisol (Ustic Kanhaplohumult, Leilehua series) and an Oxisol (Rhodic haplustox, Wahiawa series) of Hawai’i. In each soil, two additional treatments: lime + compost and un-amended soil served as control. Chinese cabbage (Brassica rapa cv. Bonsai) was used as the test plant in two greenhouse plantings, which had a factorial completely randomized design with three replicates per treatment. The results indicated that soil acidity, nutrient in the soils, plant growth and nutrient uptake were improved by the amendments compared to the control. The combined additions of biochar and compost significantly increased pH and EC; reduced exchangeable Al; reduced Mn and Fe in the Oxisol; increased P, K, and Ca content of the soils; increased Ca, Mg and Fe uptake. Exchangeable Al in the Ultisol was decreased from 2.5 cmol+/kg to nil; Mehlich-3 extractable P, K, Ca, Mg, Fe, and Mn in the Ultisol were increased by 1478, 2257, 1457, 258, 125 and 72%, respectively compared to the un-amended soil, while the same nutrients increased or decreased in the Oxisol by 180, 59, 308, -14, and -36%, respectively. Shoot and total cabbage fresh and dry matters were increased by 94, 96, 107, and 112%, respectively, as compared to the lime plus compost treatment.  Cabbage growth in the Ultisol amended with the lac tree wood biochar and vermicompost was almost twice over the lime and vermicompost treatment. Essential nutrients in the plant tissues, with the exception of N and K, were sufficient for the cabbage growth, suggesting increases in nutrients and reduced soil acidity by the additions of biochar combined with compost were the probable cause. It is recommended that locally produced biochars and composts be used to improve plant nutrient availability in the highly weathered soils. 

        In addition, the effect of placement (surface applied vs. incorporated) of biochar + compost combination on annual and perennial crops was studied in a greenhouse experiment. An Andisol (Typic hapludand, Tantalus series) and an Oxisol (Rhodic haplustox, Wahiawa series) were used, each received 4% wood-based biochar and 4% compost (volume:volume) either surface applied or mixed with the top 10-cm soil in columns having 22-cm depth and containing 1.2 L of the amended soil. Chinese cabbage (Brassica rapa, Chinensis group) and papaya (Carica papaya) served as the test crops (Figure 3). Cabbage and papaya plant height and leaf relative chlorophyll content (estimate of leaf N) were measured weekly. Cabbages were harvested at 8 weeks and oven dried. Cabbage dry weight for the incorporated amendments overall was significantly higher (p < 0.01) than the control by 19%, and by 14% for the surface application. In the Andisol there was no difference in cabbage dry weight between surface and incorporated amendments, but in the Oxisol the cabbage dry weight was significantly higher in the incorporated compared to surface and control. The root biomass in the Andisol was located throughout the 20 cm for the incorporated treatment, but in the top 10 cm for the surface applied. In the Oxisol however, both treatments showed root biomass higher in the 10-20 cm layer. Papayas were significantly (p < 0.05) taller in both amended treatments than the control for the Andisol, but not for the Oxisol. Therefore, in some soil types (movement of water and solutes was much faster in the Oxisol than in the Andisol), the application of these amendments to the soil surface will provide similar benefits to incorporating them.

Figure 3. Effect of biochar placement method (surface and incorporated) into a volcanic-ash derived soil (Andisol order, Tantalus series) in a green house trial for pak choi (Chinese cabbage, left) and papaya crops.https://www.ctahr.hawaii.edu/huen/submit_docs/Fig3.jpg

  • Objective 3. Effects of biochar on soil properties and plant growth in field trials.

   A field trial on a  highly weathered Oxisol (Wahiawa series), using a macadmia shell-derived biochar pyrolyzed 400 – 450OC purchased from Pacific Biochar Co., Hilo,Hawaii, was applied at 0, 2 and 4% (w:w) along with either urea,or organic nitrogen (N) fertilizers (blood meal: 10% N and Organic Farms:12% N). Sweet corn (Zea mays),soybean (Glycine max),and okra (Abelmoschus esculentus) served as the test crops. The N application rates were 150 and 300 kg N/ha. The experiment had a factorial design,with biochar rate as main plot, N source as subplot,and N rate as sub-subplot. There were 3 replications per treatment (Figure 4).

Our results showed that the N use efficiency markedly increased in the presence of biochar, especially for com, okra, and even soybean. The effect of biochar on plant growth seemed to extend beyond N nutrition because the treaments receiving biochar but no N input also out-yielded those having N input but no biochar as demonstrated for corn in Figure 5.

Figure 4. Biochar and N fertilizer experiment at the Poamoho field experiment (Oxisol soil, Wahiawa series) on Oahu, Hawaii.https://www.ctahr.hawaii.edu/huen/submit_docs/Fig4.jpg

Figure 5.Corn yield as affected by biochar and N fertilizer applications in a field trial on an Oxisol in Hawaii (yields were the average of two N rates: 150 and 300 kg N/ha).https://www.ctahr.hawaii.edu/huen/submit_docs/Fig5.jpg

    The long-term effects of biochar were studied again in 2019. The biochar was applied one time at the beginning of the trial in 2018, nitrogen (N) fertilizers, both organic and urea, were applied once for each growing season (total 3 seasons in 2019). The study had a split plot design with 3 replicates. Biochar application rates were randomly distributed in the main plots (31.8 x 4.5 m each), and combinations of fertilizer type and N rate  were randomly distributed in the sub-plots (4.5 x 4.5 m each). In each growing season, crop (beet, soybean and bush bean) growth and yield (leaf chlorophyll content, total biomass, and yield) and soil health parameters (root-knot nematode population, rhizobium nodule development, and CO2 level) were collected using the Solvita kit. The results showed a significant increase in the crop growth and yield by 20% under biochar application, compared to the control treatment (no biochar application). Rhizobium nodules of the legume roots significantly increased by 50% under biochar application compared to the control. Root-knot nematode’s root-galling index declined significantly with biochar application (Figure 6). The results showed a steady and significant improvement in soil health and legume crops growth and yield in the third growing season compared to the first growing season.

Figure 6. Biochar effect on root-knot nematode in beetroots grown on an Oxisol at the Poamoho Research Station, Oahu, Hawaii.https://www.ctahr.hawaii.edu/huen/submit_docs/Fig6.jpg

    We also field tested the effect of biochar on five Japanese leafy greens (Hatakena, Mitzuna, and 3 varieties of Komatsuna) on an Andisol in Maui, Hawaii. The biochar rate was 10 tons/ha applied two weeks before seedling transplanting, and triple 16 (16-16-16 N-P-K) synthetic fertilizer (at 150 kg N/ha) was applied at transplanting time along with drip irrigation. The results showed that the biochar treatment increased the fresh weight of all 5 leafy green crops by 30% and 20% over the no-biochar control during the first and second growing season, respectively (Figure 7).

Figure 7.  Combined fresh weight of five leafy greens as affected by biochar application (10t/ha).https://www.ctahr.hawaii.edu/huen/submit_docs/figure7.jpg

  • Objective 4. Publications, workshops and presentations.

  Peer-reviewed articles (acknowledgments of financial supports from Western SARE were duly mentioned).

Hue, Nguyen. 2020. Biochar for Maintaining Soil Health. In Soil Health. Giri B. and Varma A. (Eds). Springer Publ. Switzerland. Chapter 2 (in Press).

Galanti, R., Cho, A, Ahmad, A., and Radovich, T. 2019. Soil Amendments and Soil Profiling Impact on Macadamia Growth and Yield Performance. HortScience.  54(3), 519-527.

Berek A. K, Hue N.V, Radovich T. K, Ahmad A. A. 2018. Biochars improve nutrient phyto-availability of Hawaii’s highly weathered soils. Agron.  8:203-221.

Cox, J., Hue N.V, Ahmad A. A. Effects of biochar placement on the growth of Chinese cabbage and papaya seedlings. Biochar (submitted).

Web-based extension articles (published on a website http://www.ctahr.hawaii.edu/sustainag/ for the sustainable and organic agriculture program of College of Tropical Agriculture and Human Resources).

Ahmad  A. A., K. Tavares, N. V. Hue. 2019. Biochar Application to Leafy Green Varieties on Maui. Hanai’Ai (The Provider) Newsletter.

 Ahmad A. A., N. V. Hue, J. Silva, J. Uyeda, J.Sugano, T. J. K. Radovich, S. Motomura, and K.Tavares. 2019. Evaluating different varieties and biochar application rates on the yield of soybean. Hanai’Ai Newsletter.

Ahmad, A., T. Silvasy, S. Moore, C. Gangaiah, N. Hue, J. Uyeda, and T. Radovich. 2017.lmproving Seedl ing Qua lity with Locally-Made Li quid Nutrient Solution. Hana i ‘A I newletter.

Professional Presentations

Ahmad A., N. Hue, T.J.K. Radovich, K. Wang, J. Sugano, J. Uyeda, S. Motomura, J. Silva, and K. Wong. 2019. The effect of biochar application on soil health and legume crop’s growth and yield in Hawaii. American Soc. Hort. Sci. July 30 – August 4, 2019. Las Vegas NV.

Ahmad, A. A., T. Radovich, N.V. Hue., J. Sugano, J.  Uyeda, T. Silvasy,C. Gangaiah, and A. Berek. 2018. Innovative Waste Management Strategies: Uti l izing Locally Produced By- Products as Organic Amendments for Crop Production in Hawaii. Our Farms, Our Future Conference. SA REIATTRA. Apri l 3-5, St. Louis, MO. USA.

Ahmad A. , A. Berek, T. Radovich, N. Hue. 2018. Biochar as a soil amendment and nutrient regulator. American Soc. Hort. Sci. July 31- August 4, 2018.Washington DC.

 Cox J., N. Hue, A. Ahmad, K. Kobayashi. 2018. Surface applied or incorporated? Does compost and biochar placement affect plant growth and soil fertility? CTAHR Student Research Symposium. April 13-14, 2018. UHM, Honolulu, HI.

Radovich T., A. Ahmad, N. Hue, K. Wang, T. Silvasy, J. Uyeda, J. Sugano, I. Gurr, C. Gangiah and R. Paull. 2017. Optimizing local, organic compliant fertilizers for vegetable production in a crowded island environment. American Soc. Hort. Sci. Sept. 19-22, 2017. Waikoloa, HI.

Local Workshops and Field Demonstration

 Sustainable Agriculture Practices, biochar, and organic amendment applications for Better Harvests in Hawaii. Demonstration at the Taste of Hawaiian Range, Educational Booth. Local farmers and public event. Waimea, Hawaii County. 2018

Biochar benefits to soil properties and plant growth and yield. Kohala Center- Honokaa, Hawaii County. Annually for Kohala Center Trainee and the public. Field demonstration, educational booth, and presentation in April 2017, June 2018 and May 2019 (The presentation was updated with the newest results from the biochar and organic amendments research).

Biochar and organic soil amendments applications and benefits. GoFarm Waialua, Oahu County. Annual event in April. 2017-2019. GoFarm trainee and coaches for each year (The presentation was updated with the newest results from the biochar and organic amendments research).

Biochar and organic soil amendments applications and benefits. GoFarm Waimnalo, Oahu County. Annual GoFarm Trainee February 2017-2019 (The presentation was updated with the newest results from the biochar and organic amendments research).

Biochar and Sustainable Agriculture Demonstration at the Annual Meeting of Hawaii Farm Union United (HFUU) 2017 and 2018, Public event with educational booth and demonstration. Maui County.

Biochar and organic amendments benefits for orchards and ornamental plants. Honolulu Orchid Society, invited speaker for public event during the monthly meeting in Aug. 2018.

Participation Summary
2 Farmers participating in research

Education

Educational approach:

Field demonstrations on biochar + compost use/effect on crop performance were provided to local growers, particularly members of the Hawaii Organic Farmers Association (HOFA). A presentation of our work was given to professional peers at the 2017 annual meeting of the American Society of Horticultural Science (see: Radovich, T., Ahmad A., Nguyen H., Wang K., Silvasy T., Uyeda J., Sugano J., Gurr I., Gangiah C., and Paull R. 2017. Optimizing local, organic compliant fertilizers for vegetable production in a crowded island environment. ASHS Conf. 20-24 Sept. 2017, Waikaloa, Hawaii)

Educational & Outreach Activities

3 Consultations
4 Curricula, factsheets or educational tools
3 Journal articles
2 On-farm demonstrations
3 Workshop field days

Participation Summary

12 Farmers
8 Ag professionals participated
Education/outreach description:

Field demonstrations on biochar + compost use/effect on crop performance were provided to local growers, particularly members of the Hawaii Organic Farmers Association (HOFA). A presentation of our work was given to professional peers at the 2017 annual meeting of the American Society of Horticultural Science (see: Radovich, T., Ahmad A., Nguyen H., Wang K., Silvasy T., Uyeda J., Sugano J., Gurr I., Gangiah C., and Paull R. 2017. Optimizing local, organic compliant fertilizers for vegetable production in a crowded island environment. ASHS Conf. 20-24 Sept. 2017, Waikaloa, Hawaii).

 

Learning Outcomes

3 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation
Key areas taught:
  • Value of biochar in maintaining soil quality and crop yield
Key changes:
  • Selection of biochar types to match soil usage

Project Outcomes

Project outcomes:

High-N organic fertilizers could be more efficiently utilized when applied in combination with biochars than when applied alone. Our findings and recommendations would provide organic farmers some good management tools in improving their soil quality and crop yield. Furthermore, the use of biochar as a soil amendment would sequester carbon, make beneficial use of bio-wastes, and improve the environmental quality.

Ammonia loss during storage of high N, organic fertilizers could be reduced significantly by adding/mixing with 5 to 10% (by weight) of a wood-based biochar.

Recommendations:

Long-term field trials on biochar and soil health should be conducted.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.