Methods of Straw Incorporation 93

Methods of Straw Incorporation - 93
Project Leader and Principal UC Investigators Henry Studer, professor, Department of Biological & Agricultural Engineering, UC Davis Steve C. Scardaci, farm advisor, Colusa County Cooperative Extension John F. Williams, fame advisor, Sutter/Yuba Cooperative Extension	As a result of the phase down in allowable open field burning, California rice growers have been busy experimenting with different methods of incorporating rice straw into the soil. Determining the effectiveness of these methods will help growers decide which techniques will do the best job on their farms. Toward that end a UC Davis agricultural engineer is working in collaboration with two UC Cooperative Extension farm advisors. Their objectives are to: Develop a sampling and test procedure by which the effectiveness of various rice straw incorporation methods can be determined and compared. Develop physical methods to quantify the extent of straw decomposition achieved with various straw incorporation procedures. Studies were conducted at three locations. A study at a Maxwell rice farm was conducted by Colusa County farm advisor Steve Scardaci as a demonstration of several rice straw management practices. Plots were flooded, burned, straw shredded with a Dandl flail shredder, and straw chopped with a New Holland forage harvester. Soil samples were collected on April 7, 1993 with a modified gardener's type bulb planter. Samples were analyzed at UC Davis. The other two sites in the study were located near Pleasant Grove. In the first location, straw and stubble was incorporated after harvest using a stubble disk. The modified bulb planter was again used to collect soil samples on April 12, 1993. A second field was deep plowed with a moldboard in fall 1992. Soil samples were collected from this field with an 18-inch long Oakley soil probe on March 29, 1993. Analysis of the collected samples indicates that the amount of residue remaining in the fields after six months, even after overwintering, is substantial. Amounts in the deep-plowed plot appeared to be "excessively high." However, the researchers believe the amount may have been higher at the beginning of the experiment because of past tillage of the field. Design of the soil probe may also have contributed to the higher residue levels. In summary, the study showed that residue content of the soil could be determined from soil samples taken with a modified bulb planter. The sampler was simple to construct and easy to operate. The results showed that the amount of residue remaining in the spring was dependent upon the residue management practice used. Researchers also noted some variability in upper and lower sections of the soil profile at each site. The burned plots showed the least amount of residue, followed by the plot which was field chopped before stubble disking. The collection of the samples was relatively easy and proceeded quickly, compared to the amount of time required to evaluate the samples and separate the residue from the soil mass. However, the study concluded that "a truly simple and inexpensive method of measuring residue content remains to be found."

Methods of Straw
Incorporation - 93

Project Leader and Principal UC Investigators

Henry Studer, professor, Department of Biological & Agricultural Engineering, UC Davis

Steve C. Scardaci, farm advisor, Colusa County Cooperative Extension

John F. Williams, fame advisor, Sutter/Yuba Cooperative Extension

As a result of the phase down in allowable open field burning, California rice growers have been busy experimenting with different methods of incorporating rice straw into the soil. Determining the effectiveness of these methods will help growers decide which techniques will do the best job on their farms. Toward that end a UC Davis agricultural engineer is working in collaboration with two UC Cooperative Extension farm advisors. Their objectives are to:

Develop a sampling and test procedure by which the effectiveness of various rice straw incorporation methods can be determined and compared.
Develop physical methods to quantify the extent of straw decomposition achieved with various straw incorporation procedures.

Studies were conducted at three locations. A study at a Maxwell rice farm was conducted by Colusa County farm advisor Steve Scardaci as a demonstration of several rice straw management practices. Plots were flooded, burned, straw shredded with a Dandl flail shredder, and straw chopped with a New Holland forage harvester. Soil samples were collected on April 7, 1993 with a modified gardener's type bulb planter. Samples were analyzed at UC Davis.

The other two sites in the study were located near Pleasant Grove. In the first location, straw and stubble was incorporated after harvest using a stubble disk. The modified bulb planter was again used to collect soil samples on April 12, 1993. A second field was deep plowed with a moldboard in fall 1992. Soil samples were collected from this field with an 18-inch long Oakley soil probe on March 29, 1993.

Analysis of the collected samples indicates that the amount of residue remaining in the fields after six months, even after overwintering, is substantial. Amounts in the deep-plowed plot appeared to be "excessively high." However, the researchers believe the amount may have been higher at the beginning of the experiment because of past tillage of the field. Design of the soil probe may also have contributed to the higher residue levels.

In summary, the study showed that residue content of the soil could be determined from soil samples taken with a modified bulb planter. The sampler was simple to construct and easy to operate.

The results showed that the amount of residue remaining in the spring was dependent upon the residue management practice used. Researchers also noted some variability in upper and lower sections of the soil profile at each site. The burned plots showed the least amount of residue, followed by the plot which was field chopped before stubble disking.

The collection of the samples was relatively easy and proceeded quickly, compared to the amount of time required to evaluate the samples and separate the residue from the soil mass. However, the study concluded that "a truly simple and inexpensive method of measuring residue content remains to be found."