The challenge with using conventional tillage practices for onion production on muck soils is that it results in wind and water erosion of muck at a rate of one foot every 10 years, which is not sustainable for preserving these non-renewable natural resources for long-term productivity. Eroded muck contains nitrogen and phosphorous fertilizers, which pollute waterways. It is scientifically proven that erosion and subsidence decrease as ground cover increases and cultivation decreases. Therefore, growing onions in a minimum tillage system would drastically reduce the negative economical and environmental consequences of erosion, while sustaining long-term production of onions on muck soils. This project is a collaborative effort between a muck onion grower and a Cornell Cooperative Extension Vegetable Specialist. In this project, we will build on our first attempt and evaluate critical improvements required for adoption of growing direct seeded onions in a minimum tillage system on muck soil on a commercial scale. Required improvements include, i) optimizing the use of cover crops to achieve adequate ground cover; ii) optimizing the use of fertilizer including application techniques, understanding the dynamics of nutrient availability when the cover crop is winter vs. spring killed, and the potential for reducing fertilizer rates; and iii) minimizing stand losses from damping off by using seed and in-furrow fungicide treatments. Once a minimum tillage system is developed for onions grown on muck soils, growers will adopt this new technology and realize reduced losses from erosion and sustained long-term production of onions grown on muck soils.
Project objectives from proposal:
In this project, we will evaluate and demonstrate critical improvements required for adoption of growing direct seeded onions in a minimum tillage system on muck soil on a commercial scale.
See attachment for field layout, plot plans, treatment lists and evaluation plan.
Minimum tillage system establishment: A 30 acre muck field has been dedicated to this project. In September 2010, the grower cooperator seeded cover crops, winter wheat (to be spring killed) and spring barley (to be winter killed) into 10.5” rows. Minimum tillage wheat (MTW), minimum tillage barley (MTB) and the conventional planting systems were alternated in 15’ wide passes (= 3 x 5’ beds, 5 rows spaced 10.5” per bed) across the field with every other pass being MTW, and the passes in between alternating between conventional and MTB. The field will be planted into three equal 10 acre sections, each of a different variety of yellow storage onions.
For the conventional system, NPK according to a soil test will be broadcast and incorporated via disking and culti-mulching. Using the grower’s standard equipment, a barley nurse crop will be planted in 10.5” rows with the onions seeded precisely between them. The barley will be killed when the onions have one true leaf starting. For the MTW system, Roundup will be applied to kill the wheat in the spring. In both MT systems, NPK will be broadcast and incorporated using a tillivator without disturbing the cover crop residue. Then, onions will be seeded using the grower’s non-modified seeder, GPS and auto-steering technology to precisely seed the onions between the rows of cover crop residue.
Evaluation of minimum tillage systems: Each variety will be evaluated separately and divided into 5 replicates. Each replicate will be divided into 3 sections, from which sub-samples will be taken. Unless otherwise stated, data will be collected from 3 sub-samples per replicate. Ground cover – will be estimated visually and by harvesting the above-ground residue in 5’ x 5’ sub-sample areas, which will be oven-dried to obtain dry weight, at planting and once monthly until harvest. Stand establishment – in a sub-sample area 5’ x 5’, the number of onion seedlings per each of 5 rows will be counted at the flag, and 3-5 leaf stages. Fertility – a composite soil sample will be collected per replicate at the 4 and 7-9 leaf stages, and submitted to the Cornell Nutrient Analysis Lab (CNAL) for complete nutrient analysis. Available nitrate will be measured every 3 weeks using a Cardy® meter, from a composite soil sample per replicate. In mid-July, 10 random plants per replicate will be sent to CNAL for tissue analysis. Plant size – number of leaves per plant and plant height will be measured at the 2-3, 5-6 and 7-9 leaf stages. Pest pressure – number of onion thrips, Botrytis leaf blight lesions, Purple Blotch lesions and bacterial cankers per plant will be counted on 6 plants per sub-sample, as pest pressure prevails. Soil temperature and moisture – will be measured at 2” deep at a single site in each system for the duration of the growing season using WatchDog® dataloggers. Yield and grade: all of the onions in a 5’ x 5’area sub-sample will be pulled, weighed and graded. The grower will keep track of yield on a large scale. Economic analysis – the grower will provide costs for inputs and average onion selling prices.
Fertilizer application and rate trial: We will investigate banding fertilizer below the seed as an alternative to broadcasting and incorporating it in MT systems. When fertilizer is banded, rates may be reduced because it is located where it is most available to the plants, resulting in potential savings on fertilizer costs and reduced water pollution. Within each system, treatments will include: 1) 100% NPK broadcast, 2) 100% NPK banded and, 3) 75% NPK banded for a total of 9 treatments. This will be evaluated as a small-plot trial with 5 replications. In one variety, the grower will leave a 350’ x 60’ area free of broadcast fertilizer, which will include a pass of each system. Each treatment-replicate will consist of one bed wide by 20’ long with a 10’ buffer all around. Plots for the 100% NPK broadcast treatments will be selected from outside of the mini-trial area. Rates of P and K will be determined based on a soil test. The 100% rate of N will be 100 lbs. For the banded treatments, up to 100 lbs of P and up to 80 lbs of K + N will be applied in the band while the remaining NPK will be broadcast and incorporated (between the rows for MT treatments). Broadcast applications will be weighed out per treatment-replicate, spread by hand and incorporated with a hoe. Banded fertilizer applications will be made using a push seeder with a modified shoe to deliver fertilizer 3” deep. After the fertilizer bands are made, the onions will be seeded using the push seeder with its regular shoe to place the seed 1” deep. Fertility, stand establishment, plant size and yield data will be collected as described for the large-scale field trial.
Evaluation of seed and in-furrow fungicides for control of damping off: Commercially available seed treatments, 1) Pro Gro, 2) Farmore D300 and 3) Cornet + Allegiance, will be evaluated with and without Ridomil applied as an in-furrow treatment, for a total of 6 treatments. All treatments will have Pro Gro + mancozeb and Trigard for control of onion smut and maggot, respectively. Raw seed will be obtained from the seed company and seed treatments applied by Alan Taylor, Seed Technology, Cornell. It will be a small-plot set up as a randomized block design with 5 replications. The grower will leave an area one bed wide by 150 ft long not seeded in a center bed of a MTW section. Each treatment-replicate will consist of a single 20’ row. The trial will be planted using our push seeder. Stand counts will be made weekly from loop- to 2-leaf stages.