Evaluating the use of low-input technology for small-scale, no-till organic farming systems

Proposed:

Field plots were established at our collaborator's farm in spring 2016. In a randomized complete block design with four replications, winter squash was grown on beds 4 ft x 30 ft (1.2 m x 9 m) per treatment per replicate. Dr. Zinati coordinated with the collaborating farmers on field activities to ensure timely execution of treatments and collection of data.

The experimental field was flagged for three treatments: a) bare ground treatment (referred to as grower's standard), b) no-till low-input treatment (referred to as BCS), and c) no-till high-input treatment (referred to as RC). Only in plots that were flagged for the standard treatment, the cover crop was first flail mowed and then the soil was spaded twice with the Celli Spader, forming two rows per plot on May 19, 2017 (Photo 1).

Seedling beds were prepared by tilling in cover crop mixture, disking, and shaping the beds for either bare ground or laying down black plastic. No spring tillage was required for the low- and high-input technologies. Cover crop mixtures were rolled-crimped with a 2-ft wide BCS crimper or a 10-ft wide roller-crimper, respectively.

The treatments at the partnering Quiet Creek farm:

1. Grower's standard method – Bare ground treatment: includes tilled-in cover crops, transplanting with the water wheel transplanter, and seasonal mechanical cultivation;
2. No-till, low-input technology- This treatment includes rolling cover crops into mulch using a 2-ft wide walk-behind BCS roller-crimper and transplanting by hand.   The BCS is a two-wheeled small farm implement with a removable shaft to which any number of tools can be attached such as a 2-ft roller-crimper, mower or tiller;
3. No-till, high-input technology - This treatment includes rolling cover crops into mulch using a 10-ft wide roller-crimper driven by a tractor and transplanting with a no-till transplanter.

At the Rodale Institute Research Farm, in a randomized complete block design with four replications, treatments 2 and 3, mentioned above, were compared to the black plastic treatment (which includes tilled in cover crop, black plastic, transplanting with a water wheel transplanter and seasonal mechanical cultivation). Winter squash was grown in 10 ft x 50 ft beds.

Cover crop planting:

At the Good Farm, a cover crop mixture of wheat, hairy vetch and crimson clover were established in September 2016, while at Rodale Institute Research Farm, a cover crop mixture of cereal rye and Austrian winter pea were established in mid-September 2016.

Cover crop and soil sampling and assessments:

Samples of cover crop biomass were collected from 0.5 m2 quadrats on May 16, 2017, and dried in the oven for dry weight and nutrient analyses. Similarly, soil samples were collected at 0-20 cm deep, dried and sieved for chemical analysis. However, for biological analysis, samples were taken from 3 inches deep, packed in an ice chest filled with ice and transported to Rodale Institute's Laboratory and stored frozen until analysis. Similarly, soil samples were taken at the end of the season before harvest to assess for physical, chemical and biological properties. Soil bulk density and soil compaction were assessed at the beginning and the end of the season. The depths at which soil penetrometer readings of 300 psi were recorded and the averages of three readings per treatment were used to determine the depths where root growth would be restricted.

The cover crop biomass in plots that were flagged for low- and high-input technologies was rolled and crimped twice, on May 24 and June 1, 2017 (Photos 2 and 3).

Soil health measurements were taken for physical, chemical and biological properties:

• At the partnering farmers' site: composite soil samples from 0-20 cm deep were collected three times during the growing season from each treatment from 3 replications, air-dried, sieved through 2-mm sieve and sent for chemical analysis (pH, macro and micro nutrients, organic matter, carbon and nitrogen) to the Agricultural Analytical Services Laboratory (AASL) at Penn State University. For biological analysis, moist soil cores collected from 0-8 cm deep were put on ice in an ice chest and shipped overnight to Ward Laboratory for biological assessment. Soil samples were collected at beginning of the season, mid-season (first signs of fruit formation) and before harvest. At the same time, physical properties such as bulk density and compaction were determined in-house. A penetrometer was used to measure sub-surface compaction by recording the soil depth at which root penetration was hindered (300 psi).
• At Rodale Institute Research Farm: Soil samples were assessed for chemical properties and biological properties at the above-mentioned laboratories.

Crop production and weed management:

• Seedlings of butternut squash ('Waltham') were transplanted into two rows per plot with 24 inch spacing between plants using the water wheel transplanter for the standard treatment (Photo 4) and no-till planter for the rolled-crimped plots (Photo 5). All seedlings received a fish emulsion solution at the date of planting.  The Goods did not add any irrigation system to this study because they usually produce rain-fed winter squash.
• Weed species such as ragweed, foxtail, galinsoga, and pigweed compete with the young winter squash seedlings during the growing season.  The standard practice of weeding for bare ground production is two to three mechanical cultivations before winter squash plant branching exceeds bed width. Additionally, in the black plastic treatment, 1-2 seasonal cultivations between rows is typical. Treatments with cover crop mulches require no cultivation.
• Hand-hoeing and in-season cultivation were accomplished in the standard treatment on June 22 and July 10, 2017, respectively.  In the rolled-crimped treatments, weeds were only hand-weeded once.
• Weed density and biomass: Assessment of weed density (number per area) and biomass (weight per area) were conducted per treatment, replicated before transplanting, at mid-season and before harvest.  Weeds in 5.4 ft2 (0.5 m2) quadrants were counted and cut, dried at 65 oC and weighed.

Leaf and fruit sampling:

Leaf tissue samples (17 per treatment) were collected and placed in paper bags, oven- dried for four days at 55 C then ground and analyzed for nutrients at Penn State University's Agricultural Analytical Services Laboratory.

Winter squash fruits were harvested in early September 2017,cured in the greenhouse, and weighed. Fruits subsamples were collected for nutrient quality determinations after being stored for 0, 30, and 60 days.

Crop yield:

At harvest, Dr. Zinati harvested and recorded the number and weight of marketable and unmarketable fruits per treatment per replication from 20-ft long rows.

Crop nutrient quality:

Winter squash fruits per treatment were harvested at maturity and stored for 0, 30, and 60 days in a cool and dark room. At the end of each storage date, fruits were processed by removing seeds and opposite longitudinal portions of the fruits were manually prepared by peeling the skin of fruits, dicing the fresh pulp into cubes, and placing in plastic bags at -20 C. Frozen samples then were freeze-dried, using the Labconco freeze-drier, ground, and stored immediately in dark amber jars, to protect the ground samples from degradation by UV light. Subsamples were sent to Dr. Reddivari's laboratory at Purdue University for quantification of carotenoids (Lutein and a- carotene) and total polyphenols. Results are expressed as mg equivalent per g of fruit dry weight. For Polyphenols, results are expressed as mg gallic acid equivalents (GAE) per g of fruit dry weight. For mineral nutrient analyses, fruit subsamples were sent to the PSU AASL.

Rodale Institute's site:

Measurements on soil compaction were taken on April 11, 2017, followed by weed measurements, cover crop (rye and Austrian pea mix) biomass sample collection, and soil sampling for physical and chemical analyses on May 11, 2017, following the same methods listed under the grower's treatment. The cover crop in the plasticulture treatment was mowed using a flail mower and the soil was moldboard-plowed on May 11, 2017, then disked twice on May 11 and 16, 2017. The plastic mulch was laid on May 24, 2017 (representing the standard treatment) with drip irrigation. Cover crop biomass was rolled-crimped using a walk-behind BCS (representing the low-input technology treatment) and a 10-ft roller crimper front-driven by a tractor (representing the high-input technology treatment) on May 24 and June 1, 2017 (Photo 6). Seedlings of butternut squash 'Waltham' were transplanted into two rows per plot with 24 inch spacing between plants using the water wheel transplanter for the standard treatment (plastic mulch, Photo 7) on June 1, 2017 and no-till planter for the rolled- crimped plots (Photo 8) with drip irrigation on June 7, 2017. All seedlings received fish emulsion solution at planting.

Weed-free areas were established on July 11, 2017 and weed counts were recorded in 0.5 m2 quadrats. Compaction measurements using a penetrometer were taken on August 15, 2017. Leaf tissue samples were taken on July 6, 2017. Winter squash fruits were harvested from weed-free areas on August 30, 2017. Fruits were cured in the greenhouse for two weeks and subsamples of marketable fruits per treatment were weighed and stored at 0, 30, and 60 days in a dark cool room. At the end of each storage period, fruits were cut open and sections from the edible portion were stored at -20 °C. Frozen samples were freeze dried and will be sent to Dr. Lavanya Reddivari's Laboratory at Purdue University for carotenoid analyses and to the PSU AASL for nutrient analysis.

Statistics and data presentation:

Weed biomass and density, crop yield and quality, and soil health per site were assessed. Collected data on weed, yield, crop nutrient content, soil quality indicators, and profitability were e compiled, and analyzed by standard ANOVA using the generalized linear model (GLM) of SAS® 9.3. Estimated economic benefits of each system were prepared based on inputs such as hours and cost of weeding, cultivation, farmer return, profit and benefits gained for soil health. Analyzed data were presented in tables and written in technical and scientific formats (see outreach section).

Expectation of proposed method:

We expected to demonstrate the pros and cons of the reduced-tillage proposed method in comparison to the standard cultivation method and provide the partner growers and vegetable growers with results that allow them make informative decisions to conserve soil health and produce crops with high nutrient value.