Progress 10/01/10 to 09/30/11
Outputs
Progress Report Objectives (from AD-416) The Objectives of this proposal are to investigate 1) the levels of total and available copper in selected rice fields and how they compare to levels in soils from natural wetlands and 2) the efficacy of a non-copper algicide and copper/adjuvant combinations for controlling species of algae that are known to occur in California rice fields, particularly those that are tolerant to copper. Approach (from AD-416) To accomplish objective 1, we will collect samples from twenty rice fields spread across a wide geographic area that includes the rice growing region in northern California. The fields to be sampled will be selected after consultation with rice farm advisors and the principle investigators of Project RM-4 (the van Kessel project). The selection procedure will consider soil type, cropping history and other factors. Prior to the addition of water to rice fields, we will collect five soil samples equally spaced along a transect that bisects each field. The location of each sample will be recorded with a sub-meter Trimble XRS-Pro GPS unit. These samples will be sent to the UC DANR Analytical Laboratory and analyzed for total copper and DPTA extractable copper (i.e. , potentially available copper). Similar samples will be collected from ten natural wetlands within the same region. We will avoid sampling wetlands with a history of rice production. The hypothesis that total copper and DPTA available copper in these two types of systems differ will be compared statistically using analysis of variance. This information will allow us to determine the extent that copper levels in rice fields differ from those in natural wetlands. Research continued on the control of algae in rice fields, primarily using cultural practices. It was found that the best way to minimize negative effects of algae is to restrict the amount of fertilizer moving into the standing water in the fields. Improved methods of fertilizer incorporation and optimizing the timing of application made the most significant improvements. These methods were made available to farmers through local cooperative extension programs.
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Progress 10/01/09 to 09/30/10
Outputs
Progress Report Objectives (from AD-416) The Objectives of this proposal are to investigate 1) the levels of total and available copper in selected rice fields and how they compare to levels in soils from natural wetlands and 2) the efficacy of a non-copper algicide and copper/adjuvant combinations for controlling species of algae that are known to occur in California rice fields, particularly those that are tolerant to copper. Approach (from AD-416) To accomplish objective 1, we will collect samples from twenty rice fields spread across a wide geographic area that includes the rice growing region in northern California. The fields to be sampled will be selected after consultation with rice farm advisors and the principle investigators of Project RM-4 (the van Kessel project). The selection procedure will consider soil type, cropping history and other factors. Prior to the addition of water to rice fields, we will collect five soil samples equally spaced along a transect that bisects each field. The location of each sample will be recorded with a sub-meter Trimble XRS-Pro GPS unit. These samples will be sent to the UC DANR Analytical Laboratory and analyzed for total copper and DPTA extractable copper (i.e. , potentially available copper). Similar samples will be collected from ten natural wetlands within the same region. We will avoid sampling wetlands with a history of rice production. The hypothesis that total copper and DPTA available copper in these two types of systems differ will be compared statistically using analysis of variance. This information will allow us to determine the extent that copper levels in rice fields differ from those in natural wetlands. Documents Trust with CA Rice Research Board. Log 39169. The agreement was established in support of Objectives 1 and 2 of the in- house project, the goal is to develop management practices to minimize damage caused by cyanobacteria and algae to aquatic ecosystems used for rice production in northern California. Experimental results from 2009 indicated that delaying the application of the phosphate containing fertilizer normally used in rice production by 19 to 30 days noticeably reduced the abundance of nuisance algal growths and phosphate dissolved in the water. We selected several checks from rice fields farmed by growers located north and west of Gridley, California. Checks were assigned to one of the following treatments: conventional, i.e., surface applied followed by a roller or 30 day delay, i.e., P fertilizer applied aerially 30 days after sowing. The amounts of P-fertilizer applied were approximately 41 kg ha-1 (46 lb acre-1) as P2O5. The fields were flooded during the week of May 19, 2009. Shortly thereafter, we began to sample the fields for PO4-P and algal abundance. In four of five experimental sites, PO4-P concentrations in water samples collected from fields which received the delayed P fertilizer application were lower than in fields which received the conventional P-fertilizer application. The difference between the two application methods ranged from 16% to 66% decrease in the fields that received the delayed P-fertilizer application. Water phosphate concentrations increased dramatically following an aerial application of P-fertilizer at the end of the delay period. For most fields this was about 30 days after sowing, but for one field it was 19 days after sowing. Algal abundance was lower for the delayed P fertilizer checks and was about one-half of that for the conventional P-fertilizer treated checks, but increased dramatically following the delayed fertilizer application. These results are consistent with previously measured responses of algae and water phosphate in California rice fields. They provide a novel method for reducing problems associated with algal growth in rice fields. This novel method has been adopted by rice growers. ADODR monitored progress through site visits and meetings.
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