Progress 09/01/99 to 08/31/04
Outputs
The overall goal of this research is to investigate various strategies, from a biological and economic systems perspective, for making the transition from conventional to organic systems of agricultural production. Five strategies for transition for conventional to organic systems are being evaluated in addition to a conventional control. Harvest for both starts is now complete. A wide range of Parameters have been measured and include: aboveground biomass of cover crop and cash crop, nutrient and energy flows, soil quality indices (physical, chemical, biological), decomposition, soil microbiological properties, insects, weeds, disease, crop yield and quality, soil microarthropods, soil entomopathogens, and economics. There was no significant differences in yield between treatments in the first year soybean crop, and organic soybeans produced similar yields to conventional. There was higher insect damage in organic sweetpotates than conventional in the first start but
no differences in marketable yield with data averaged over both years. There were significant differences in wheat and in the second year of the student the conventional wheat outyielded the organic wheat. Microbial biomass and activity were more sensitive to changes in soil management practices than total C and N. In the first two years, the ORG was most effective in enhancing soil microbial biomass C and N among the transition strategies, but was accompanied with the highest yield losses. By the third year, soil microbial biomass C and N in the reduced input transition strategies were significantly greater than those in the CNV (averaging 32 and 35 percent higher, respectively), although they were slightly lower than those in the ORG (averaging 13 and 17 percent lower, respectively). Soil microbial activity and net N mineralization in all transitional systems were significantly higher than those in the CNV (averagely 83 and 66 percent greater, respectively), with no differences
among the various transition strategies. These findings suggest that the transitional strategies that gradually reduce chemical inputs can serve as alternatives that minimize economic hardships as well as benefit microbial growth during the early stages of transition to organic farming systems.
Impacts
This research will facilitate an understanding of the interactions of inputs and biological factors that can be managed to reduce economic risk for growers transitioning to organic agriculture.
Publications
- No publications reported this period
|
Progress 10/01/02 to 09/30/03
Outputs
The overall goal of this research is to investigate various strategies, from a biological and economic systems perspective, for making the transition from conventional to organic systems of agricultural production. Five strategies for transition for conventional to organic systems are being evaluated in addition to a conventional control. The 1st start is complete, and harvest has just been completed for the 3rd year cabbage crop. A wide range of Parameters are being measured and include: aboveground biomass of cover crop and cash crop, nutrient/energy flows, soil quality indices (physical, chemical, biological), decomposition, soil microbiological properties, insects, weeds, disease, crop yield and quality, soil microarthropods, soil entomopathogens, and economics. Soil MBC and MBN were significantly affected by the transition strategies. By the second year (2001), MBC and MBN were significantly higher in the organic than other treatments. Compared to the
conventional treatment, MBC and MBN were 49-52% and 20-62% higher in the organic plots, respectively. The microbial biomass C-to-N ratio (MBC/MBN) was affected by the different strategies in 2001, but not in 2002. However, there were higher MBC/MBN ratios (6.3-7.5) in 2002 than in 2001 (3.8-5.5). The treatments significantly affected microbial activity (respiration rate) in both 2001 and 2002. Compared to the Conventional, the organic and gradual reduction had almost equally highest microbial respiration (74-100% above the control), followed by the organic fertilizer, organic weed management, and organic pesticide treatments. (24-79% higher than the control). Major weed species included pigweed, broadleaf signalgrass, sicklepod, largecrabgrass wild radish, and prickly sida. As one measure of weed pressure, the average count per plot was obtained for each crop in each start, averaging over multiple sampling dates for the crop. A split-split plot analysis of variance, with start as the
whole plot factor, treatment as the sub-plot factor, and crop as the sub-sub plot factor, was carried out on these average counts (for the major species combined) and also on log transformed values. A contrast comparing the no herbicide treatments (2, 4) with the treatments where herbicide was used (1, 3, 5) is significant (p=.005). The mean count (per .5 m sq) in no-herbicide treatments exceeds that in the herbicide treatments by 3.8. Critical weed free periods for organic sweepotatoes were determined to be between 2 and 6 weeks after transplanting sweetpotatoes. Much of the economic work on the NRI project during the past year has been based on generating annual crop budgets for each of the six treatments, laying the foundation for systems budgets that will eventually encompass multiple years and crops. To generate the budgets, we combined data from field trials, input prices from conventional NCSU crop budgets, and output prices from USDA.
Impacts
This research will facilitate an understanding of the interactions of inputs and biological factors that can be managed to reduce economic risk for growers transitioning to organic agriculture.
Publications
- Seem, J.E., Creamer, N.G., and Monks, D.W. 2003. Critical Weed-Free Period for Beauregard Sweetpotato (Ipomoea batatas). Weed Tech. 17:686-695.
|
Progress 10/01/01 to 09/30/02
Outputs
The overall goal of this research is to investigate various strategies, from a biological and economic systems perspective, for making the transition from conventional to organic systems of agricultural production. For the 1st start in the experiment, now in the 3rd yr with a winter wheat/fall cabbage sequence of the overall rotation, soil quality parameters were unaffected by treatment. Nevertheless, and similar to results from 2001, there was a trend for greater soil respiration(evolved CO2) and more rapid infiltration in the organic compared to conventional systems. Likewise penetrometer resistance, a measure of soil compaction, tended to be greater in the conventional system. The same pattern of results was evident in the 2nd start of the experiment, now in the 2nd yr with a crop sweetpotato, but with significant differences noted between the conventional and both organic/transitional organic treatments. Management inputs and practices for sweetpotato occurred
nearer the time of soil sampling compared to those for winter wheat, thus reflecting greater treatment divergence in our measurements. In 2002, we measured heterotrophic (microbial) respiration, microbial biomass C and N, soil extractable N, and N mineralization in the transitional agroecosystem experiment. Soil respiration, microbial biomass C and N, and net N mineralization were highest in the organic soil and lowest in the conventional soil, with the transitional treatments being the middle of these two extremes. These effects were more obvious in the middle season (late June samples) than in the early season (early April) and the late season (early September). Total bacteria, fluorescent Pseudomonads and Burkholderia populations were not affected by treatments but did fluctuate with time of sampling. Year and date of sampling dramatically impacted the number of culturable bacteria. There was a consistent trend of higher populations in spring with falling numbers in summer months,
rising again in the fall. Burkholderia were the exception Where treatment means were found to be significantly different, Treatments 2 ("cold turkey" organic), 3 (- synthetic fertilizers), and 6 (gradual transition) were most often found to have the highest populations. These three treatments all received manure compost. In soybean in 2000 and 2001 there was no difference in the average number of sentinel insects infected with insect-parasitic nematodes and fungi. There were no significant differences among treatments for insect-pathogens in 2003. Much of the economic work on the NRI project during the past year has been based on generating annual crop budgets for each of the six treatments, laying the foundation for systems budgets that will eventually encompass multiple years and crops. To generate the budgets, we combined data from field trials, input prices from conventional NCSU crop budgets, and output prices from USDA. The budgets report returns over variable costs by treatment
and repetition for Start I soybeans and sweetpotatoes, and Start II soybeans.
Impacts
This research will facilitate an understanding of the interactions of inputs and biological factors that can be managed to reduce economic risk for growers transitioning to organic agriculture.
Publications
- Mueller, J.P., Barbercheck, M. E., Bell, M., Brownie, C., Creamer, N., Hitt, A., Hu, S., King, L., Linker, H.M., Louws, F.J., Marlow, S., Marra, M., Raczkowski, C. W., Susko, D. J. and Wagger, M.G. 2002. Development and Implementation of a Long-Term Agricultural systems Study: Challenges and Opportunities. HortTechnology 12:362-368.
- Seem, J. 2002. Critical Weed-Free Period for 'Beauregard' Sweetpotato (Ipomoea batatas) and Weed Seedbank Changes in Response to Transitioning from Conventional to Organic Farming Systems. M.S. Thesis. North Carolina State University.
|
Progress 10/01/00 to 09/30/01
Outputs
In 2001, sweetpotato was planted in the experiment that was initiated in 1999, and soybean was planted in the experiment that was initiated in 2000. Cover crops of rye and vetch proceeded the sweetpotato in treatments 2, 3, and 6, and rye proceeded the soybean in all plots in 2001. Primary differences in soybean production were cultivations substituting for herbicides in plots 2, 4, and 6. Based on soil tests, no additional fertility was required in soybean plots. Sweetpotato plots differed on all input categories. In plots 2, 3, and 6, fertility was managed with inputs of rye/vetch and compost. Plots 1, 3, and 4 were fumigated with Telone II. Lorsban was applied in plots 1, 3, and 4. Herbicides were applied to plots 1, 3, and 5. Soils were sampled to a depth of 15 cm at five geo-referenced sampling points per plot on 27 Mar, 26 Jun, and 24 Jul. Approximately 30 cores from each sampling point were combined and divided for analyses of soil chemical and biological
parameters. Cover crop biomass was measured on 30 April. Insects and diseases were scouted weekly through the season. Weeds densities were counted in .5 m2 frames 4 m from each geo-referenced sampling points on 13 Jul, and 16 Aug for soybeans, and on 30 Jul and 7 September for sweetpotatoes. Weed biomass was collected at harvest. In addition, a baseline weed seedbank analysis was conducted. Aboveground biomass was collected for soybean and sweetpotato just prior to harvest (4 Oct and 1 Oct repsectively). Yield was determined by collecting two, 3.3 m row samples of soybeans (1 Nov) and sweetpotato (1 Oct) next to each sampling point. Soybeans were threshed, weighed, and analyzed for percent moisture, Sweetpotato were graded, rated for insect damage, weighed, and stored for further disease evaluation. Preliminary Results: There were no significant differences between soybean yields or biomass in 2000. In 2001, yield (p=.06) and percentage insect damage (p=.07) of number 1 sweetpotatoes
tended to be lower in the conventional treatment than in the other treatments. There were no significant differences in abundance of any group of soil inhabiting nematodes. All groups of nematodes increased over the growing season in 2001. In soybean in 2000 and 2001 there was no difference in the average number of sentinel insects infected with insect-parasitic nematodes and fungi. There was a trend (p=.07) for the abundance of soil microarthropods to be greater in the organic treatment as compared to the other treatments. In 2001 in sweetpotatoes there was no difference in average number of sentinel insects infected with insect-parasitic nematodes and fungi. There was a trend (p=.08) for the average number of sentinel insects infected with insect parasitic nematodes in the pesticide removal treatment to be greater than in the fertilizer removal and gradual reduction treatments. In 2000 there were few treatment effects on measures of soil microbial activitiy. In 2001, CO2 evolution,
microbial biomass carbon and nitrogen, C:N ratio were all higher in the organic treatment compared to all of the other treatments in the first two sample dates.
Impacts
This study will help farmers select an economically and biologically viable transition strategy for converting from conventional to organic agricultural systems.
Publications
- No publications reported this period
|
Progress 01/01/00 to 12/31/00
Outputs
This report summarizes methodology. Many samples are still being processed since the implementation season has just ended. Neverthe less, it was a very successful first year for both crop production and sample collection. Treatment management: Following a conventional corn crop in 1999, rye was planted over the entire experimental area on 30 November, 1999. Rye planting was delayed due to flooding from Hurricane Floyd. On 17 April, herbicide (glyphosale) was applied to treatments 1, 3, and 5, and rye was mowed in treatments 2, 4, and 6. Rye was chisel plowed and disked in all treatments on 4 May. On 22 May, the seed-bed was prepared with a "S-tine" cultivator and inoculated soybeans (NKS5711) were planted in all treatments on 76 cm rows. Treatments 1, 3, and 5 received a pre-emergent herbicide (chlorimuron-ethyl + metribuzin) on 23 May. Treatments 2, 4, and 6 were rotary hoed on 1 June, and cultivated with a sweep cultivator on 9 June. A post emergent herbicide
(chlorimuron-ethyl) was applied 21 June to treatments 1, 3, 5, and 6, while treatments 2 and 4 were cultivated again on 22 June. Sampling: Soils were sampled to a depth of 15 cm at five geo-referenced sampling points per plot on 27 Mar, 13 June, 17 July, and 12 Sept. Approximately 30 cores from each sampling point were combined and divided for analyses of soil chemical and biological parameters. Insects and diseases were scouted weekly through the season. Weeds were sampled on 8 June, 6 July, and 14 August. At each date, 0.5 meter frames were placed 4 m from each geo-referenced sampling point. The same area was counted each sampling date by species, and above ground biomass was collected at the last sampling date. Just prior to harvest, plots were visually rated for percent weed cover and soybeans were given a lodging score. Aboveground biomass was collected for cover crop just prior to planting, and for soybean on 21 Sept. Soybean samples were weighed and subsampled to determine pod,
stem, and leaf biomass. Each plant part was analyzed for N. Yield was determined by collecting two, 3.3 m row samples of soybeans next to each sampling point (27 Oct). Soybeans were threshed, weighed, and analyzed for percent moisture. On 1 Nov., soybeans were combined and yields determined for diagnostic soil area and whole plot.
Impacts
This is the first year, and data has yet to be analyzed for the baseline so as yet there is no impact.
Publications
- No publications reported this period
|
Progress 01/01/99 to 12/31/99
Outputs
This study is just being initiated. An interdisciplinary team of scientists has received funding from USDA NRI Agriculture Systems program to begin a 4 year project studying the transition from conventional to organic systems. Thirteen faculty and three graduate students representing horticultural science, crop science, soil science, entomology, plant pathology, agriculture and resource economics, and statistics will collaborate to study six strategies of transition. Biological and economic parameters will be measured. A three-year rotation has been selected which includes soybean, sweet potato, and tomato/cabbage. The experiment will have two starts (1999 and 2000) to insure replication in time. Soils have been intensively mapped and georeferenced. Sampling points will be georeferenced as well so that soils can be collected from the same points by the various disciplines and analyzed over time. Rye was planted over the experimental area in Fall of 1999, and soybeans
will be planted this May. Baseline sampling will begin in early March.
Impacts
As the demand for organic products continues to grow, many growers are interested in transitioning from conventional to organic systems. This study aims to provide information about the most economical and biologically desireable strategy for making the transition.
Publications
- No publications reported this period
|
|