Investigating methods of preventing soil loss in a potato:grain rotation system using cover and nurse crops

View the project final report

Commodities

• Agronomic: barley, potatoes

Practices

• Crop Production: cover crops, crop rotation
• Education and Training: extension
• Production Systems: general crop production

The potato production systems in the Northeast are predominantly two-year rotations of potato and small grains (barley, oats, or wheat).  With a short growing season, potato production in the Northeast doesn’t provide much opportunity for cover-cropping, with potato harvest occurring during the last half of September through the first half of October.  In the grain production phase of the rotation, the practice of post-harvest primary tillage dominates the region in order to provide early preparation and planting of the subsequent potato crop in the spring. With our current production system there are several points where the risk for soil loss is high.  With little crop residue and potentially compacted soils from field traffic, the period after potato harvest is of one concern.  Another is the late summer/fall tillage of small grain ground eliminating crop stubble or regrowth of underseedings (clover, annual ryegrass).  This practice exposes soils to potential erosion and runoff from fall rains and spring snowmelt.  Lastly, the time period from potato planting to row-closure is sensitive to erosion and runoff events and has recently gained prominent attention in recent years owing to our increase in early summer high-intensity rain events (> 2” per hour events) causing significant damage to fields and roadsides, and leading to visible water pollution issues.    

Goal 1:  Assess the capacity of nurse crops to hold N and protect soil from eroding prior to potato hilling.

Objective 1- determine optimum nurse crop species and planting rate to obtain optimum efficiency. 

Objective 2- assess optimum method and timing of nurse crop destruction

Goal 2: Assess the effects of alternative methods to cover cropping and primary tillage timing on small grain yields, potato yields, and production efficiency. 

Objective 3- determine most effective and efficient methods for fall cover and primary tillage preceding a potato crop using either underseeding or cover cropping.

Objective 4- assess economic feasibility of cover crop and tillage methods.

Nurse Crop Trials

We will establish nurse crop trials at the two University of Maine Experiment Station farms (Orono, ME and Presque Isle, ME).  We will evaluate seeding rate, seed type, and destruction dates and methods of the nurse crop in two replicated trials.  Cereal rye and spring oats will be used as the nurse crops with seeding rates equating to 0.5, 1.0, 1.5, and 2.0 million plants per acre.  Nurse crop destruction methods of herbicide, hilling/cultivation, and herbicide plus hilling will be compared.  We will grow round white potatoes at the Orono location and Russet Burbank potatoes for the Aroostook county location.  Each of those varieties are typical for the area.  Plot areas will be established, seed spread by hand and incorporated with a tine cultivator.  Then plots will be marked and hand planted.  Seed will be covered with planter discs. 

At approximately 21 to 24 days after planting (6”-8” potato plant height), above and below-ground nurse crop biomass will be collected by plot (two 2-ft² samples per plot) to assess production prior to destruction.  A separate strip of plots will be sampled and destroyed at 30 days after planting.  We will collect soil samples for nutrient analysis and nurse crop N status will be assessed by NDVI prior to killing, and potato crop N status will be assessed at 4 and 8 weeks after hilling. 

Yield samples will be taken a month following top-kill.  Potatoes will be graded to US number 1 and total yield.  Ten potatoes will be sampled for skin quality and internal defect.  Experimental treatments will be replicated five times.

Cover Crop Method and Tillage Timing Trials

We will compare current conventional tillage potato/grain production to a modified version of the research conducted by Griffin et. al., that would include underseeded vs. monocropped small grains.  Underseeded (annual ryegrass) plots would include treatments of postharvest tillage (late summer), late fall chemical desiccation, or spring tillage.  Monocropped plots would include treatments of fall tillage, fall tillage plus spring oat cover, fall tillage plus cereal rye cover with spring chemical desiccation, or spring tillage of monocrop stubble. 

Plots (grain phase) will be established at the Aroostook Experiment Station in spring of 2017.  The seven treatments will be organized as a randomized complete block design with four replications.  Grain yields and quality parameters will be recorded. Fall and spring ground cover will be recorded preceding the potato phase.  Spring ground temperatures and moisture levels will be recorded for individual treatments. Russet Burbank potatoes will be planted in the spring of 2018.  Yield and quality parameters will be recorded in the fall at harvest.

Local standard crop care practices (pesticide applications, cultivation) will be conducted by research farm staff. 

Comparative cropping budgets will be estimated for each treatment of the cover crop/tillage timing trial to assess the potential return to growers for adoption of a particular practice. 

Educational Activities

Twilight Meeting- We propose to conduct a twilight meeting at the Aroostook Experiment Station in which we will send invitations to our grower mailing list (300 potato growers).  We will likely look to conduct this in July 2017 and July 2018.  We will conduct a presentation on the research, current observations, and provide a brief tour of the plots.  We expect 15-20 growers to attend these meetings each year.

Maine Potato Conference- The annual Maine Potato Conference is conducted each January in Caribou, ME.  We propose to provide one to two presentations on this research for the 2018 and/or 2019 conferences.  Approximately 200 growers, consultants, and university staff and faculty attend each year.

Maine Grain Conference- The Maine Grain conference is conducted annually during the month of March.  We propose to provide a presentation at this conference in 2018.  Approximately 60-80 growers, consultants, and university staff and faculty attend each year.

Maine Grain and Oilseed Newsletter- We propose to write an article about this research and demonstration that will be disseminated through this newsletter (700+ subscribers including potato mailing list).