Conventional vs. regenerative almond orchards, with regards to invertebrate biomass and biodiversity, soil health, food safety, and profitability

Final report for GW19-193

Project Type: Graduate Student
Funds awarded in 2019: $25,000.00
Projected End Date: 07/31/2021
Host Institution Award ID: G164-20-W7503
Grant Recipient: California State University East Bay
Region: Western
State: California
Graduate Student:
Major Professor:
Major Professor:
Dr. Patty Oikawa
California State University East Bay
Dr. Erica Wildy
California State University East Bay
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Project Information

Summary:

Regenerative agriculture has the potential to increase biodiversity and promote key biological processes while reducing farmer investment in mechanical and chemical inputs over conventional monoculture production systems. Almonds are the dominant crop in California agriculture in terms of acreage and revenue generated. This study provided an innovative systems-level comparison of best management practices in regenerative and conventional almond production in Central CA. This 2-yr study: 1) Characterized the soil quality and biodiversity in almond production systems, with a special focus on soil carbon and pest management services; 2) Measured the relative yield and profitability of regenerative and conventional almond systems; and 3) Disseminated results to producers using a variety of learning tools. A character matrix of practices was used to designate orchards as regenerative or conventional. In replicated plots, soil organic matter, total soil carbon and nitrogen, microbial biomass and diversity, water infiltration, and bulk density were measured. Insect communities on the soil surface, and pest damage to the nuts were quantified. Producer surveys provided the basis for a cost/benefit analysis of each orchard. The Community Alliance with Family Farmers (CAFF) and Ecdysis Foundation/Blue Dasher Farm have been working the share the study’s findings via the organizations’ networks. By providing clear and transparent empirical assessment of these two systems, this project hopes improve the profitability of farmers, improve the natural resource base on almond orchard, and increase the quality of life for farmers and their communities.

Project Objectives:

The overall goal of this research was to provide critical data and education that removes perceived barriers for the adoption of regenerative almond production systems. Specific objectives of the proposal include:

  • Characterize the soil quality and biodiversity present on regenerative and conventional almond production systems, with a special focus on soil carbon and pest management services.
  • Measure the relative yield and profitability of regenerative and conventional almond systems, identifying key cost and benefits of the two systems.
  • Disseminate results to producers using a variety of learning tools, including web-based documents, presentations at grower meetings, in-person field days, interviews with local and national media outlets, and peer reviewed scientific articles.
Timeline:

Cooperators

Click linked name(s) to expand
  • Sara Tiffany - Technical Advisor (Educator)

Research

Materials and methods:

Experimental site selection

Plots (n = 4) were established on each orchard. The plots were 40 × 40 m and separated by at least 15 m, resulting in 64 total observation points for the study. Plots were established 20 m into the orchard to avoid field margin effects.

Invertebrate community assessments

The epigeal invertebrate communities were sampled using quadrats ( Jonathan G. Lundgren, Shaw, Zaborski, & Eastman, 2006), that were placed at two random locations in the inter-row areas of each plot. Sampling of the invertebrate communities occurred during the bloom, fruit development, and harvest periods. The invertebrate communities that could be collected from the soil surface and top 2 cm of the soil with aspirators in 15 min were stored in 70% ethanol. The biomass of the invertebrates per 0.5 m2 were weighed, and invertebrates were identified to the morphospecies level. Voucher specimens are all housed in the insect collection at Blue Dasher Farm, Estelline, SD.

Pest Density/Damage

We assessed the insect pest damage on 500 almonds per farm in 2018 and 600 almonds per farm in 2019, (< 20 from any one tree), from the orchard floor (Bentley et al., 2001; Doll, 2009; Legner & Gordh, 1992). The almonds were each categorized as having: no pest damage, navel orange worm damage (Amyelois transitella), ant damage (Formicidae), oriental fruit moth damage (Grapholita molesta), peach twig borer damage (Anarsia lineatella), leaf footed plant bug or stinkbug damage (Coreidae, Pentatomidae), and unknown pest damage.

Total Soil Carbon and Nitrogen (0-60cm)

Soil samples (60 cm deep)  samples were taken at a random location in each plot (Geisseler & Horwath, 2016). The probe (2.54 cm × 91.44 cm Plated Replaceable Tip Probe w/ 61 cm Window and Hammer Head Handle) was inserted 60 cm deep and the resulting soil samples (2.28 cm diameter) were partitioned to 0-5, 5-10, 10-15, 15-30, 30-45, and 45-60 cm depths. Samples were weighed to the nearest 0.1 g, and then were air dried. before being prepared for elemental analysis of total soil carbon (TSC) and total soil nitrogen (TSN). The air-dried weight of the soil was recorded to 0.01 g. Ground samples were passed through a sieve with 0.180 mm openings. For each soil depth, three sub-samples underwent elemental analysis (ECS 8020, NC Technologies, Milan, Italy). To calibrate the analysis, each sample tray consisted of five bypass samples (12-15 mg of soil), two blanks, and four standards, 0.5-2.0 mg (Acetanilide, Costech, Valencia, CA), followed by the soil samples. Mass (Mg) of TSC per depth layer was calculated using the Equivalent Soil Mass (ESM) method (Wendt & Hauser, 2013). This resulted in the assessment of carbon as Mg of TSC/ha at the following ESM layers, with the average calculated depth to reference mass in parentheses: 500 Mg (6.1 cm), 1,000 Mg (11.0 cm), 1,500 Mg (15.8 cm), 3,000 Mg (30.4 cm), 4,500 Mg (45.2 cm), and 6,000 Mg (59.2 cm).

Surface Bulk Density

Bulk density (BD) samples were taken in three plots per farm, following the protocol outlined by the NRCS (NRCS, 2017). A metal tube 7.62 cm wide and 12.7 cm tall was hammered to a depth of 8 cm. The volumes of soil in each core were estimated, and the samples were transferred to paper bags in the laboratory. Wet and dry weights of each soil core were recorded to the nearest 0.01 g and used to calculate BD and the soil’s gravimetric moisture percentage.

Soil Texture

The Web Soil Survey was used to select similar soil types for the conventional-regenerative orchard pairings (NRCS, 2021.). Additionally, the soil samples (> 200 g) used to determine bulk density were analyzed for their sand, silt, and clay percentages using the hydrometer technique (Oregon State University-Central Analytical Laboratory- Standard Operating Procedures, 2017) .

Our analysis informs us that there was no difference in soil textures between treatments, with no correlation between matrix score and clay percentage. The mean, median, and standard for the farms’ sand silt, and clay percentages is found in Table 1.

Water Infiltration Rates.

Water infiltration rates were measured in one plot of each of the 2019 orchards (four regenerative and four conventional) during the bloom and fruit development stages of the crop. We followed the NRCS protocol, where 444 mL of water were poured into a sheet-metal ring (15.2 cm diam, 13.5 cm tall), which was hammered  6.5 cm into the soil (Doran, 1999). The time until all the water saturated into the soil was recorded to the nearest second.

Soil Macro and Micronutrients, Soil Organic Matter (SOM), Soil pH, the Haney Soil Health Score, and Soil Respiration.

Soil pH, soil macro and micronutrients, Haney soil health scores, and soil respiration were quantified in each orchard (Ward Laboratories, Kearney, NE). Soil cores (15 cm deep, 1.9 cm diam.; n = 16), were taken from the four replicate plots, totaling 16 samples per farm during the fruiting period of the orchard. To determine SOM, the Loss on Ignition (LOI) technique was used. Soil pH is quantified using the slurry method with a 1:1 ratio soil: water. Soil respiration, soil nutrients levels, and the Haney Soil Health Score were measured on samples that were dried at 50˚ C. The samples were ground to pass a 2 mm sieve and divided into three subsamples (two were 4 g each and one weighed 40 g. The 40 g soil sample is analyzed with a 24 h incubation test at 24o C. This sample is wetted through capillary action by adding 20 mL of deionized water to a 237 mL glass jar and then capped. After 24 h, the gas inside the jar was analyzed using an infrared gas analyzer (IRGA) (Li-Cor 840A, LI-COR Biosciences, Lincoln NE) for CO2-C. The two 4 g samples were extracted with 40 mL of deionized water and 40 mL of H3A, respectively. The samples were shaken for 10 min, centrifuged for 5 min, and filtered through Whatman 2V filter paper. The water and H3A extracts (Haney, Haney, Hossner, & Arnold, 2006) were analyzed on a flow injection analyzer (Lachat 8000, Hach Company, Loveland CO) for NO3-N, NH4-N, and PO4-P. The water extract was also analyzed on a Teledyne-Tekmar Torch C:N analyzer for water-extractable organic C and total N. The H3A extract was also analyzed on a Thermo Scientific ICP-OES instrument for P, K, Mg, Ca, Na, Zn, Fe, Mn, Cu, S and Al (Haney Test – Ward Laboratories Inc., 2020.).

PLFA Analysis

Phospholipid fatty acid (PLFA) testing provides an index of a soil’s microbial biomass and composition (Frostegård, Tunlid, & Bååth, 2011). Soil cores (10 cm depth, 1.9 cm diam; n = 16), were taken from four replicates per site, totaling 16 samples per farm. This sampling occurred during the fruiting period. The samples were taken at random locations within each replicate, at least 5 m apart, using a transect that diagonally bisected the plot. The microbial biomass and community composition were recorded, and noting the total microbial biomass, undifferentiated microbial biomass, total bacteria, gram-positive bacteria, actinomycetes, gram-negative bacteria, rhizobia bacteria, total fungi, arbuscular mycorrhizal fungi, saprophytic fungi, and protozoa.

 

Ground Cover

The ground cover height and composition in each of the replicates/plots were recorded during each of the three sampling periods.  The percent ground cover was categorized as 0-25%, 25-50%, 50-75%, and 75-100%. Percent ground cover in the overall orchard was assessed using visual assessments of the percent ground cover in each invertebrate quadrat.  The community composition and whether the ground cover was resident vegetation or planted was determined using information from the farmers and direct field observations. 

Management Practices

A producer survey was used to determine management practices, costs and revenues that contribute to the direct net profitability of each operation (See supplemental materials for a copy of the survey). The factors used for determining profit were the production costs and material inputs, labor, and revenue. Under production operating costs, the study includes costs associated with winter sanitation, sampling for tree nutrient status and soil salinity, pH, and nutrient levels, irrigation and frost protection,  fertilizers, insecticides, herbicides, fungicides, disease treatment sprays, trapping vertebrate pests, cover crop seed/bag, tillage, mowing, flamers, grazers, and harvest. Within the harvest category the study accounts for: people hours to conduct the harvest and/or the price paid to external contractors, kernel kg/ha, returns, and additional revenue streams such as almond hulls and co-products, as well as returns on harvesting the grazing livestock (Klonsky et al., 2016).  No farm in the study reported additional revenue from grazers or additional revenue streams such as almond hulls. Two regenerative orchards reported revenues from selling value added products, such as almond butter. Under labor and operating costs, the study includes people hours worked (Klonsky et al., 2016). The 2016 labor rate for machine operators in almond orchards is $22.40/h and $15.40/h for non-machine operators. We used the mean, $18.90/h of these to incorporate people hours worked into overall orchard costs (Yaghmour et al., 2016). This was not a complete economic analysis as it does not account for cash overhead (insurance, taxes) and non-cash overhead (capitol recovery). Additionally, within the operating/cultural costs category the study did not account for the cost of pollination, custom pruning, and the cost of fuel for operating machinery (only propane for burning weeds).

Statistical Analyses

Unless otherwise noted, data are reported as mean values followed by +/-SE and α = 0.05. Analyses were performed in R (R development Core Team, https://www.r-project.org/, version 4.0). The study used the lme4 package to create the General Linear Mixed Models (GLMM) (Bates et al., 2015). To calculate the biodiversity indices we used the vegan: Community Ecology package (Oksanen et al., 2019). For non-parametric statistical calculations and comparing models the study used the RVAideMemoire: Testing and Plotting Procedures for Biostatistics and the Modern Applied Statistics with S. Fourth Edition packages (Brian et al., 2002; Hervé, 2020). For linear regression analysis and performing the Bonferroni Outlier Test, the analyses used the Companion to Applied Regression (car) package (Fox & Weisberg, 2019). The R base package was used for the multivariate analyses and the micompr R package (Fachada, 2018) was used to ensure the assumptions were met for those analyses. The R package Rstatix (Kassambra, 2020) was used to determine collinearity. The R base package and ggplot2 (Wickham et al., 2020) were used for the Principal Component Analysis (PCA).

We tested the effect of  orchards being defined as regenerative(Matrix Score ≥ 5) or conventional, as well as the orchards’ regenerative vs. conventional matrix scores (higher the score the more regenerative the orchard) on invertebrate biomass, invertebrate abundance, Arthropoda abundance, the Shannon-Wiener Index (H’ ) diversity indices, pest damage, TSC, TSN, bulk density, water infiltration rates, macro and micronutrients, microbial communities, yield, revenue, costs, and profitability. As appropriate General Linear Mixed Models, One-way ANOVA and Welch Two Sample t-tests were used to determine significance. In certain cases where the data and the residuals were not normally distributed the non-parametric Mood’s Median Test was utilized. MANOVA was used to confirm the patterns in soil and biological response variables that were revealed by our univariate assessments and investigate whether or not colinearity among the response variables was a driver of these relationships.  Principle Component Analysis (PCA) was used to assess the relationship among the soil quality and biological metrics, as well as the role of certain management practices in determining those metrics. 

Research results and discussion:

Results

Regenerative orchards had lower soil bulk densities(N = 16; R2adj = 0.45, F2, 13 = 7.02, treatment P = 0.004, clay P = 0.21)  and infiltrated water faster than their conventional counterparts(N = 8; R2adj = 0.45,  F1, 6 = 6.74, P = 0.04) (Fenster, Oikawa, & Lundgren, 2021).  

The soils in regenerative orchards contained higher levels of total phosphorus, inorganic phosphorus, available phosphorus, calcium, and sulfur, while receiving higher Haney soil quality scores. Compared to conventional orchards, regenerative orchards had 32% more TSC and 19% more TSN, with the majority of the TSC and TSN in the 0-30 cm layer. Through the 0-6000 Mg ESM layer (Total TSC Mg /ha) regenerative orchards had 54.52 ± 4.76 Mg TSC/ha, while conventional orchards contained 41.37 ± 7.27 Mg TSC/ha (Fenster, Oikawa, & Lundgren, 2021). This study did not conduct a carbon life cycle analysis, but since regenerative orchards contained an additional 13.15 Mg/carbon/ha (48.26 Mg/CO2 equivalents/ha), 30% more than their conventional counterparts,  this suggests that regenerative management in almond orchards could contribute to potential carbon sequestration initiatives (Fenster, Oikawa, & Lundgren, 2021).

The duration that these orchards had been in their respective systems had significant effects on soil carbon. When we modeled TSC in the 0-6,000 Mg ESM layer in relation to time, regenerative management correlated with the buildup of TSC (N = 49; treatment: χ21 = 8.07; P = 0.005; clay: χ21 = 33.00; P < 0.001), and years under conventional management correlated significantly with reductions in TSC (N = 49; treatment: χ21 = 10.20; P = 0.001; clay: χ21 = 42.13; P < 0.001).

Ground cover was the parameter best correlated with TSC through the soil column. Multiple regression models revealed that keeping 75-100% of the ground covered with vegetation was the sole practice that scaled with TSC through the 6,000 Mg ESM layer (N = 16; R2adj = 0.78, F7, 8 = 8.79, model P = 0.003, ground coverage P = 0.01, clay P = 0.01).

Soils in regenerative orchards had larger total microbial biomass, total bacterial biomass, Gram (+) biomass, and Actinobacteria biomass (Fenster, Oikawa, & Lundgren, 2021) . For most of these microbial community metrics there was no statistical difference between the regenerative and conventional orchards (P > 0.05). Conventional orchards never had improved microbial community structure than regenerative orchards.

Plant cover on the orchard floor was significantly larger in regenerative orchards. In regenerative orchards, the median ground coverage percentage category was 75-100% and for conventional orchards it was 0-25% (N = 16; χ21 = 9.14, Mood’s P = 0.002) (Fenster, Oikawa, & Lundgren, 2021). Additionally, regenerative orchards averaged more plant species on the floors of their orchards. The mean number of plant species on the orchard floor in regenerative orchards was 7.0 ± 0.7 and in conventional orchards it was 2 ± 0.7 (N = 16; R2adj = 0.60, F1, 14 = 23.14, P < 0.001) (Fenster, Oikawa, & Lundgren, 2021).

Regenerative orchards had significantly larger (N = 16; t13 = -3.86, P = 0.002), richer (N = 16; t12 = -4.13, P = 0.001) and more diverse invertebrate communities (N = 16; t13 = -3.34, P = 0.01) (Fenster, Oikawa, & Lundgren, 2021). Pest damage to the almonds was similar in the regenerative and conventional orchards (P > 0.05). The GLMM’s (Zero Pest Damage(Re) ×   Diversity(F) + Farm(Ra)) for the stricter criteria, zero pest damage, found  significant correlations between invertebrate diversity (N = 40;  χ21 = 7.34, P = 0.01) and species richness (N = 40; χ21 = 4.18, P = 0.04) and reduced pest damage.  The GLMM’s (No Serious Pest Damage (Re) ×   Diversity(F) + Farm(Ra)) for the less strict criteria, no serious pest damage, also found significant correlations between H’ (N = 40; χ21 = 5.50, P = 0.02) and species richness (N = 40;  χ21 = 4.23, P = 0.04) and reduced pest damage.

There was no difference in nutrient composition (P > 0.05) or yield (P > 0.05) among regenerative (1,338 kg/ha ± 248)  and conventional orchards (1,920 kg/ha ± 315) (N = 14; t11 = 1.45, Welch P = 0.17). However, regenerative orchards were about twice as profitable as their conventional counterparts ($5,299 ± 1,090 vs $2,877 ± 733 per ac) (N = 13; t9 = -2.32, P = 0.045). The operating costs of regenerative orchards were $3,402 ± 425 per ha and for conventional orchards they were $2,494 ± 90.32 per ha (N = 15; t6 = -0.86, P = 0.42). Gross revenue of regenerative orchards was $18,178 ± 3,033 per ha and for conventional orchards it was $9,587 ± 1,851 per ha (N = 13; t8 = -2.42, P = 0.04).

Discussion

Almond orchards under regenerative management saw improvements to soil quality and increased biodiversity and profitably (Fenster, Oikawa, & Lundgren, 2021). Most of the soil quality metrics (soil carbon/nitrogen and micronutrient levels, water infiltration rates, and soil health indices) were enhanced on regenerative orchards compared to their conventional counterparts  (Fenster, Oikawa, & Lundgren, 2021). The microbiology, plant community, and invertebrate metrics (including earthworms) were greater in regenerative systems. Pest damage to the nuts were similar in the regenerative and conventional orchards, with increasing invertebrate biodiversity correlating to reduced pest damage  (Fenster, Oikawa, & Lundgren, 2021). Of all the management practices analyzed via multiple regression, permanently maintaining orchard floor ground cover was significantly correlated with TSC at the 0-6,000 Mg ESM layer (Fenster, Oikawa, & Lundgren, 2021). Although maintaining ground cover is important, multi-functional almond orchards require an integrated system of regenerative practices to be productive (Fenster et al., 2021). Overall almond nutrient levels and yields were similar in the regenerative and conventional systems  (Fenster, Oikawa, & Lundgren, 2021). Profits were nearly doubled in the regenerative systems relative to their conventional counterparts  (Fenster, Oikawa, & Lundgren, 2021). Principal Component Analysis showed that improvements to the soil and biological properties of the orchards were interconnected and produced by combining multiple management practices, rather than just by one or two practices  (Fenster, Oikawa, & Lundgren, 2021).

The performance of the regenerative orchards can be attributed to them combining multiple regenerative practices into a single operation. Their gains were not due to any one management practice  (Fenster, Oikawa, & Lundgren, 2021). Rather, increasing the number of regenerative practices correlated to improved performance (Fenster et al., 2021) , with Principal Component Analysis, showing that permanent ground coverage, the avoidance of synthetic agrichemical inputs, and the use of organic amendments correlated with improvements to the soil health and biodiversity metrics (Fenster, Oikawa, & Lundgren, 2021). This suggests that there may be a  foundational set of practices that need to be implemented for there to be improvements in soil quality and biological community metrics. One would assume  that Principal Component Analysis would show avoiding tillage to be a key management practice. However, since 88% of the orchards in the study did not till this seems to signal that abstaining from tillage on its own will not improve critical soil quality and biological metrics. The success of regenerative orchards is due to these agroecosystems being more robust, with additive or synergistic interconnections among the system’s components  (Fenster, Oikawa, & Lundgren, 2021). This is illustrated by the fact that soil bulk density, TSC, TSN, TSP, microbial biomass, actinobacteria biomass, invertebrate H’, and invertebrate biomass were all correlated to one another, with regenerative management driving these interconnections  (Fenster, Oikawa, & Lundgren, 2021). These results suggest that converting agriculture over to regenerative systems could be part of the solution to several imminent global problems, including climate change, diminishing water resources, biodiversity loss, agricultural pollution, human health problems, and diminishing rural economies.

References

Bates, D., Mächler, M., Bolker, B., & Walker, S. (2015). Fitting Linear Mixed-Effects Models Using lme4. Journal of Statistical Software, 67(1), 201–210. https://doi.org/10.18637/jss.v067.i01

Bentley, W. J., Hendricks, L., Duncan, R. A., Silvers, C., Martin, L., Gibbs, M., & Stevenson, M. (2001). BIOS and conventional almond orchard management compared. Calif. Agric., 55(5)(5), 12–19. https://doi.org/doi:10.3733/ca.v055n05p12

Bianchi, F. J. J. A., Booij, C. J. H., & Tscharntke, T. (2006). Sustainable pest regulation in agricultural landscapes: A review on landscape composition, biodiversity and natural pest control. Proceedings of the Royal Society B: Biological Sciences, Vol. 273, pp. 1715–1727. https://doi.org/10.1098/rspb.2006.3530

Brian, A., Venables, B., Bates, D. M., Firth, D., & Ripley, M. B. (2002). Modern Applied Statistics with S. Fourth Edition. https://doi.org/ISBN 0-387-95457-0

Dainese, M., Martin, E. A., Aizen, M. A., Albrecht, M., Bartomeus, I., Bommarco, R., … Steffan-Dewenter, I. (2019). A global synthesis reveals biodiversity-mediated benefits for crop production. Science Advances, 5(10), eaax0121. https://doi.org/10.1126/sciadv.aax0121

Doll, D. (2009). Taking a harvest sample for orchard IPM check-up - The Almond Doctor. Retrieved September 13, 2017, from UCANR website: http://thealmonddoctor.com/2009/09/08/taking-a-harvest-sample-for-orchard-ipm-check-up/

Doran, J. (Soil Q. I. (1999). Soil Quality Test Kit Guide. Retrieved from United States Department of Agriculture website: https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb1044790.pdf

Eilers, E. J., & Klein, A.-M. (2009). Landscape context and management effects on an important insect pest and its natural enemies in almond. Biological Control, 51, 388–394. https://doi.org/10.1016/j.biocontrol.2009.07.010

Fenster, T. L. D., LaCanne, C. E., Pecenka, J. R., Schmid, R. B., Bredeson, M. M., Busenitz, K. M., … Lundgren, J. G. (2021). Defining and validating regenerative farm systems using a composite of ranked agricultural practices. F1000Research, 10, 115. https://doi.org/10.12688/f1000research.28450.1

Fenster, T. L.D., Oikawa, P.Y, & Lundgren, J. G. (2021). Regenerative almond production systems improve soil health, biodiversity, and profit. Frontiers in Sustainable Food Systems. https://doi.org/10.3389/FSUFS.2021.664359

Frostegård, Å., Tunlid, A., & Bååth, E. (2011). Use and misuse of PLFA measurements in soils. Soil Biology and Biochemistry, 43(8), 1621–1625. https://doi.org/10.1016/J.SOILBIO.2010.11.021

Geisseler, D., & Horwath, W. R. (2016). Soil Sampling in Orchards. Davis.

Grebliunas, B. D., Armstrong, S. D., & Perry, W. L. (2016). Changes in water-extractable organic carbon with cover crop planting under continuous corn Silage production. Air, Soil and Water Research, 9, 45–54. https://doi.org/10.4137/ASWR.S30708

Haney, R. L., Haney, E. B., Hossner, L. R., & Arnold, J. G. (2006). Development of a New Soil Extractant for Simultaneous Phosphorus, Ammonium, and Nitrate Analysis. Communications in Soil Science and Plant Analysis, 37(11–12), 1511–1523. https://doi.org/10.1080/00103620600709977

Haney Test - Ward Laboratories Inc. (n.d.). Retrieved February 20, 2020, from https://www.wardlab.com/haney-test/

Hervé, M. (2020). RVAideMemoire: Testing and Plotting Procedures for Biostatistics. Retrieved from https://cran.r-project.org/package=RVAideMemoire

John, A., Weisberg, S., Price, B., Adler, D., Bates, D., Baud-bovy, G., … Winsemius, D. (2019). Companion to Applied Regression, Third Edition. Retrieved from https://socialsciences.mcmaster.ca/jfox/Books/Companion/

Klonsky, K., Sumner, D. A., Stewart, D., & Gutierrez, C. (2016). 2016 SAMPLE COSTS TO PRODUCE ORGANIC ALMONDS. Retrieved from https://coststudyfiles.ucdavis.edu/uploads/cs_public/24/7c/247c069c-8290-4060-aa96-3e556b0f339b/16almondorganicnsjvfinaldraft42716.pdf

LaCanne, C. E., & Lundgren, J. G. (2018a). Regenerative agriculture: merging farming and natural resource conservation profitably. PeerJ, 6, e4428. https://doi.org/10.7717/peerj.4428

LaCanne, C. E., & Lundgren, J. G. (2018b). Regenerative agriculture: Merging farming and natural resource conservation profitably. PeerJ, 2018(2), e4428. https://doi.org/10.7717/peerj.4428

Legner, E. F., & Gordh, G. (1992). Lower Navel Orange worm (Lepidoptera: Phycitidae) Population Densities Following Establishment of Goniozus legneri (Hymenoptera: Bethylidae) in California. Journal of Economic Entomology, 85(6), 2153–2160. https://doi.org/10.1093/jee/85.6.2153

Lundgren, J. G., & Fausti, S. W. (2015). Trading biodiversity for pest problems. Science Advances, 1(6), e1500558–e1500558. https://doi.org/10.1126/sciadv.1500558

Lundgren, Jonathan G., Shaw, J. T., Zaborski, E. R., & Eastman, C. E. (2006). The influence of organic transition systems on beneficial ground-dwelling arthropods and predation of insects and weed seeds. Renewable Agriculture and Food Systems, 21(04), 227–237. https://doi.org/10.1079/RAF2006152

NRCS. (2017). Soil Quality: Indicators: Bulk Density. Retrieved November 27, 2017, from Soil Quality for Environmental Health  website: http://soilquality.org/indicators/bulk_density.html

NRCS (2021) Web Soil Survey.: by USDo Agriculture.

Oksanen, J., Guillaume Blanchet, F., Friendly, M., Kindt, R., Legendre, P., McGlinn, D., … Wagner, H. (2019). Vegan: Community Ecology Package. R Package Version 2.5-2.6. Retrieved from https://cran.r-project.org/package=vegan

Oregon State University-Central Analytical Laboratory- Standard Operating Procedures. (2017). Retrieved from http://oregonstate.edu/ehs/sites/default/files/pdf/lab_safety_requirements.pdf

Ryals, R., & Silver, W. L. (2013). Effects of organic matter amendments on net primary productivity and greenhouse gas emissions in annual grasslands. Ecological Applications, 23(1), 46–59. Retrieved from https://www.marincarbonproject.org/file/2018-documents/2_Effects-of-organic-matter-amendments-on-net-primary-productivity-and-greenhouse-gas-emissions-in-a

Soil Survey Staff (Natural Resources Conservation Service United States Department of Agriculture). (n.d.). Web Soil Survey. Retrieved February 13, 2020, from https://websoilsurvey.sc.egov.usda.gov/App/HomePage.htm

USDA-NRCS. (1998). Estimating Soil Moisture by Feel and Appearance. Retrieved from ftp://ftp-fc.sc.egov.usda.gov/MT/www/technical/soilmoist.pdf

Weil, R., & Brady, N. (2017). The Nature and Properties of Soils. 15th edition.

Wendt, J. W., & Hauser, S. (2013). An equivalent soil mass procedure for monitoring soil organic carbon in multiple soil layers. European Journal of Soil Science, 64(1), 58–65. https://doi.org/10.1111/ejss.12002

Yaghmour, M., Haviland, D., Fichtner, E., Sanden, B., Viveros, M., Sumner, D., … Gutierrez, C. (2016). Sample Costs to Establish an Orchard and Produce Almonds. In University of California Agricultre and Natural Resources Cooperative Extension Agricultural Issues Center UC Davis Department of Agricultural and Resource Economics. Retrieved from https://coststudyfiles.ucdavis.edu/uploads/cs_public/27/59/27599258-3e53-4e5f-aefb-08d12f5b0cb9/16almondssjvnorthfinaldraft81116.pdf

Zhang, M., He, Z., Zhao, A., Zhang, H., Endale, D. M., & Schomberg, H. H. (2011). Water-extractable soil organic carbon and nitrogen affected by tillage and manure application. Soil Science, 176(6), 307–312. https://doi.org/10.1097/SS.0b013e31821d6d63

Zsolnay, A. (1996). Dissolved Humus in Soil Waters. In Humic Substance in Terrestrial Ecosystems (pp. 171–223). https://doi.org/10.1016/B978-044481516-3/50005-0

Participation Summary
13 Farmers participating in research

Educational & Outreach Activities

12 Consultations
2 Curricula, factsheets or educational tools
2 Journal articles
1 Online trainings
3 Published press articles, newsletters
5 Webinars / talks / presentations
1 Workshop field days

Participation Summary:

1114 Farmers
1181 Ag professionals participated
Education/outreach description:

To date we have presented the results of the project at a variety of conferences and webinars, as well as doing a virtual field day. At the EcoFarm conference the preliminary results of this project were presented as part of the keynote address by Dr. Lundgren (1/9/2020) and a pre-event full day workshop (1/8/2020), while Tommy Fenster presented a poster on this project (1/9/2020). Before the California Small Farms Conference Dr. Lundgren presented the preliminary results of this project at the Cal Poly San Lois Obispo Sustainable Agriculture Lecture Series (2/27/2020). At the California Small Farms Conference Tommy Fenster, Dr. Lundgren, and Ward & Rosie Burroughs (two of the farmers in the study) conducted a conference workshop based around the preliminary results of this study (2/28/2020). On 2/29/2020 a large beekeeper we work with who works with a number of Almond growers in the Central Valley, took us out to consult with several farmers he supplies bees to about the study’s findings. On 7-16-2020 Dr. Lundgren and Ward and Rosie Burroughs (two of the farmers in the study) lead a webinar hosted by Chico State Regenerative Ag and Science program discussing the preliminary findings of this study.

Originally, our plan was to host two Farmer field days (one in the Northern range and one in the San Joaquin Valley) with the Community Alliance of Family Famers on regenerative farming in almond orchards. However, due to Covid-19 we transitioned to a webinar field day format. CAFF had successfully executed several of these webinars to date, so we reached out to Western SARE staff and were granted approval to switch to a webinar format for our farmer field day. This virtual field day occurred on 10/7/2020. There were 83 attendees on the zoom call with additional people tuning in via Facebook live. The CAFF staff reported that this was their best attended in person or virtual field day to date.  Additionally, it was posted to YouTube (https://www.youtube.com/watch?v=yYfCe5hkcwo),  where as of 7/30/2021 it has had 503 views and 11 likes.  The farmers who participated were Ward and Rosie Burroughs (Merced County), Wes Sperry (Merced County), Glenn Anderson (Merced County), and Brian Perry (Yolo County). The Burroughs have been operating a ~1,000-acre regenerative system for a number of years and provided valuable insights to the participants on what they have found to work for them over the years. Wes Sperry is a neighbor of the Burroughs whose conventional orchard was a part of this study. Further because of sharing the preliminary findings of this study with Wes in 2019 he began to transition one of his blocks from a conventional to a regenerative system. These two speakers provided workshop participants with key farmer resources who can speak to both what an established system looks like as well as the transition process for large acreage operation. Glenn Anderson has been farming regeneratively since 1983. He has a 13-acre operation and makes his income via direct marketing to consumers. Brian Perry also has a direct-to-consumer almond operation on 12.5 acres that he has been farming since 2010. Further, he has been bringing sheep into his orchard each spring to control biomass and cycle nutrients. Between these four farmers we believe that we were able to provide participants with a diverse range of knowledge regarding regenerative management in almond orchards.

As part of the registration for the webinar we were able to collect a brief survey. 169 people registered for the webinar, of which 70 people indicated that they were famers. These 70 farmers reported that they farm ~30,420 acres. Additionally, there was a farm consultant who reported that he advised on 100,000 acres of farmland. All the farmers indicated that there were interested in implementing a range of regenerative management practices. We sent out a post-event survey, of which 7 people responded. Of those 7 who responded, three were farmers. Two of those farmers said that because of the webinar they were very likely to integrate regenerative practices. The first of these farmers listed applying compost and using cover crops as the two regenerative practices they planned on implementing. The other farmer listed cover crops, no-till or reduced tillage, crop-livestock integration, hedgerows, compost application as the practices they planned on adapting. The third farmers listed they were somewhat likely to implement regenerative practices, listing using cover crops as the practice they were likely to implement.

Originally, we stated that "results from the study will be shared via the CAFF and Ecdysis Foundation: Blue Dasher Farm websites, social media accounts, and e-newsletters from the beginning of 2020 through the spring of 2020." However, due to Covid-19 the lab at Cal State East Bay was shut down until August of 2020. This delayed the completion of some of the results. Instead of submitting the papers from the study in the Spring of 2020 we submitted the first paper in December of 2020 and second paper in February of 2021.  Both papers have been accepted. The first was published on 2/15/2021 in the Faculty1000 Journal. The title of the paper is Defining and validating regenerative farm systems using a composite of ranked agricultural practices (https://f1000research.com/articles/10-115). As of 9/7/2021 this manuscript had been cited four times. The second manuscript was accepted on 6/28/2021 and was published on 8/10/2021 in the journal, Frontiers in Sustainable Food Systems. The title of the second manuscript is Regenerative almond production systems improve soil health, biodiversity, and profit (https://www.frontiersin.org/articles/10.3389/fsufs.2021.664359/full).  As of 9/7/2021 the article had been viewed 3,362 times. Further it had an Altmetric score of 53, placing it in the top 5% of all research outputs scored by Altmetric. The Ecdysis foundation has shared multiple social media posts on the findings from the two manuscripts,  and as a result the findings from this project. Dr. Lundgren did an interview on the No-Till Farmer podcast and Tommy Fenster was interviewed by Comstock Magazine for an article they did on regenerative agriculture (https://www.comstocksmag.com/longreads/regenerating-our-soil). Additionally, CAFF shared a newsletter that presented a summary of our webinar and as well as additional resources for farmers.

Finally, because of the success of the project the Ecdysis Foundation has received funding to replicate this study across the Central Valley, as well as study orchards transitioning from conventional to regenerative management. This project began in March of 2021 and to date includes 30 farms. Of these farms, 11 operations are transitioning from conventional to regenerative management, 14 are established conventional operations, and 5 are established regenerative operations. This Phase II project will involve collaborations with numerous almond producers, General Mills, UC Davis researchers, and USDA-ARS.

Project Outcomes

6 Farmers reporting change in knowledge, attitudes, skills and/or awareness
1 Farmers changed or adopted a practice
4 Farmers intend/plan to change their practice(s)
1 Grant received that built upon this project
Did this project contribute to a larger project?:
Yes
6 New working collaborations
Project outcomes:

To date we have presented the findings of this project at a number of conferences, via webinars, and the network we have built with famers and beekeepers. The first manuscript from this project has been cited four times and the most recent manuscript currently has an Altmetric score of 53, placing it in the top 5% of all research outputs scored by Altmetric. The results from this study indicate that when farmers take a regenerative systems based approach they create a more diverse and ecologically farming system with the biology of the system providing the same effect as synthetic inputs in conventional systems. Further, these regenerative systems provide key ecosystem services while reducing the negative environmental health impact to the farm community. For example, this study finds that regenerative almond systems have equivalent yields to conventional systems, no differences in pest damage (positive correlation of invertebrate community to reduced pest damage). This is all while being twice as profitable, holding more carbon, having more robust and diverse invertebrate communities, and infiltrating water more effectively. We hope that these results and the associated outreach can demonstrate to farmers that a transition to sustainable agriculture not only improves the environmental health of their farms, but also their farm’s economic outlook, while making their farms more resilient to abiotic and biotic pressures. Finally, expanded research began this year to replicate this first study across the Central Valley, with a particular emphasis on landscape level water and carbon dynamics in collaboration with numerous almond producers, General Mills, UC Davis researchers, and USDA-ARS. This Phase II study will also produce roadmaps for orchards wishing to transition from conventional to regenerative production systems.

Knowledge Gained:

This project has been an incredible learning experience for me. Since, at the time of the project I was a master’s student this was my first research project, and this project taught me how to plan and execute a research project involving sustainable agriculture. I have learned that sustainable agricultural systems may vary by practices, but it is key for sustainable systems to take a systems level approach where multiple sustainable practices are working hand in hand to create a system where the whole is greater than the sum of the practices. Farmers cannot just add one sustainable practice and expect to have a sustainable system. Further, going into this project I hypothesized that the sustainable systems would see significantly lower yields than the conventional systems. However, seeing the results from this project and then extensively reviewing the literature on regenerative agriculture and talking to farmers practicing regenerative systems I learned that regenerative systems could have equivalent yields, while supplying key ecosystem services.

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.