Soil Amendment - Crop Rotation Effects on Productivity - Soil Properties Within Potato Production Systems

Soil Amendment - Crop Rotation Effects on Productivity - Soil Properties Within Potato Production Systems

Summary

Objectives:
1a. Research will be conducted on the effects of crop rotation and soil amendments (compost, manure, and paper mill sludge). For soil amendments, special emphasis will be on effects occurring several years after applications have ceased (i.e. residual effects), because these effects will be critical to the economic viability of soil amendment use on commercial farms.
1b. Farmers will identify critical questions concerning the commercial use of soil amendments and rotation crops. They will help design and conduct trials using soil amendments and new crop rotations on commercial potato farms.
1c. An economic analysis of the research data will be completed and results of the entire project will be disseminated to the Maine potato industry via presentations, discussion groups, and publication of an Extension fact sheet.

2. Water infiltration rates, runoff, and sediment removal will be compared for several crop rotation schemes and for amended versus non-amended soils under potato production.

Results to date
Experiments on crop rotation and amendment use were conducted at Aroostook Research Farm in Presque, ME. Soil samples were collected and analyzed for inorganic N, mineral nutrients, organic matter, bulk density, and water stable aggregates. Laboratory results are currently being analyzed. Plant tissue samples were collected and are being analyzed for nutrient content. The following is a brief description of the experiments and 1999 yield/quality results:
Crop Rotation, Compost, and Manure Effects on Potato Production Systems (Experiment 1). This study compared the following compost (10 t A-1)and manure (20 t A-1) amendment treatments: i) untreated check; ii) amended during 1996 only; iii) amended from 1992-1995 only; iv) amended each cropping year since 1992. Two-year rotations of potato-oats versus potato-green manure (P/V/O – pea/vetch/oats) were also compared as were treatments with supplementary irrigation treatments. Contrary to past years, amendment and irrigation did not significantly increase potato yields during 1999. US#1 yields for the four respective amendment treatments were 302, 324, 318, 318 cwt/A. As we have observed in this study in past years, potatoes within two-year rotations performed as well following oats as following green manure. There were no major effects of rotation crop or amendment on tuber quality. The results of this experiment do not support past results showing significant current-season and residual soil amendment benefits.
Crop Rotation Comparison and Residual Effects of Compost and Paper Mill Sludge. (Experiment 2). This study compared the following crop rotations: i) continuous potatoes; ii) two-year 1:1 potatoes-oats; iii) two-year 1:1 potatoes-vegetables; iv) three-year, potatoes-oats-timothy/clover; and v) amended two-year 1:1 potatoes-oats. The amended treatment was a measure of residual amendment effects. Compost (10 t A-1)and paper mill sludge (60 t A-1)) had been applied during 1996. Results during 1999 documented positive residual effects of the 1996 amendment treatments. US#1 potato yields were highest (252 cwt/A) in the amended treatment and they significantly exceeded yields in the potatoes-oats rotation (211 cwt/A) and the continuous potato rotation (188 cwt/A). These beneficial effects were observed three growing seasons after treatments were applied. Compared to several of the other treatments, tubers were larger in the amended treatment and presumably more valuable. US#1 yields in the three-year rotation (242 cwt/A) were also significantly higher than the continuous potato treatment; however, tuber size was relatively small and specific gravity was low in this treatment, presumably due to higher N availability from the previous timothy/clover rotation crop.
These experiments will be repeated during the 2000 growing season and the results form the 2000 growing seasons and prior years will be used to conduct an economic analysis for amendment use in potato systems.

UMCE’s Matt Williams and John Jemison have continued to work with a group of Maine dairy and potato growers to identify the research needs concerning amendment, manure, and crop rotation use. In addition to the existing groups, audiences at the March 13 and 14, 2000 soil health potato school talks in Houlton and Fort Kent, ME were used to obtain grower input for research and demonstration projects for the 2000 growing season. Grower trials looking at extended crop rotations (Dan Corey Farm in Littleton, ME) and manure use on dwarf corn as a rotation crop for potatoes (Perry Lilley Farm in Smyrna, ME) are planned for the 2000 season. Experiments have been continued on the Donald Fitzpatrick Farm in Houlton, ME (a test of multiple rates of paper mill sludge vs. a control). Based on grower interest, a two-year study of liquid manure use on potato in central Maine was completed during 1999. Solid manure and pH effects on potatoes were studied in central Maine during 1999. This study will be repeated during the 2001 growing season.
A number of field days and presentations were conducted in 1999, and similar events are planned for the 2000 growing season and fall 2000/winter2001. An economic analysis of the project results will be conducted after the results from the 2000 growing season are available. A UM Cooperative Extension fact sheet will prepared after the 2000 growing season results are available.
Runoff and infiltration were measured in amended versus unamended plots during summer 1999 using a moveable rainfall simulator. Each test was conducted on 1 m2 target area after hilling and when the potato plants had full canopy cover. The precipitation rate used was 3.6 cm h-1. The rainfall test was run until the runoff rate stabilized on each measured plot and 1 L runoff samples were collected at 10 minutes and 30 minutes after runoff began. The total sediment weight of each sample was determined. The filtered liquid was analyzed for total N, inorganic N, and dissolved phosphate-phosphorus. The sediments were analyzed for total nitrogen and algal available phosphorus.
Calculations on infiltration parameters are in progress. Runoff volumes over time will be subtracted from the total rainfall within the target area. The resulting values will be an estimate of the infiltration volumes over time. The infiltration volume over time will be fit to a modified Kostiakov equation to determine parameters that describe the infiltration curve. The modified Kostiakov parameters will be compared to determine differences between treatments.
Results of the chemical analysis showed that the sediment in the amended treatments had higher total N (pr<0.10). The runoff from the amended plots was higher in NH4-N (pr<0.05) and dissolved phosphate-phosphorus (pr<0.10). Other measured chemicals and the weight of sediments from each sample were not significantly different. Similar measurements will be conducted during the 2000 growing season. The sample size will be increased to allow greater resolution of treatment effects. Reported March 2000.