Good alfalfa yields and salinity control
Long-term research is going beyond the known fact that alfalfa can effectively control saline seeps. Scientists are trying to find out what cultivars give the best salinity control along with the highest yield.
“Alfalfa roots penetrate deeply into the soil and can extract over 20 inches (50 centimetres) of moisture every year. This lowers the water table so less ground water flows to the saline seep,” said soil salinity specialist Von Wentz.
But different alfalfa cultivars differ markedly in rooting depth, soil water extraction and yield. Each cultivar also performs differently in different soil zones.
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As well, recommended alfalfa cultivars for salinity control are based on research done in Montana before 1980 when many of today’s improved varieties weren’t available.
Wentz and and Surya Acharya of Agriculture Canada are comparing 12 alfalfa cultivars at three Alberta sites. Brown soil plots are at Oyen, dark brown soil polts are at Lethbridge and black soil plots are at Mundare. They were initially seeded in 1994. Over the next six years, the research team will monitor rooting depth, soil moisture and yields for the 12 cultivars
The study is comparing Beaver, a common alfalfa cultivar, with four verticillium wilt-resistant cultivars, one multi-leaf cultivar, three dryland varieties and three Flemish types.
A report on the first year of this project appears in the Irrigation and Resource Management Division Applied Research Report, 1994-1995 available from the conservation and development branch at 403-422-4385.
– Alberta Agriculture
Irrigated alfalfa needs fertilizer too
Farmers often don’t fertilize irrigated alfalfa because it has a reputation as a crop that improves soil fertility. However, six years of research show the opposite is true.
Colin McKenzie, an Alberta Agriculture soil and water agronomist working on the question, said alfalfa especially under irrigation requires and removes large quantities of nutrients from the soil.
An average irrigated alfalfa crop, about four and a half tons per acre, removes 12.3 kilograms of phosphorus and 100 kg of potassium per acre. An average irrigated wheat crop, 60 bushels per acre, takes about 6.8 kg of phosphorus and 9.5 kg of potassium per acre.
Between 1989 and 1993, nearly 100 irrigated alfalfa fields in the Brooks, Vauxhall and Bow Island areas were sampled. The survey confirmed that fertilizer rates used on alfalfa were much less than the nutrients the crops used.
The survey indicated fewer than one-third of farmers applied sufficient phosphorus to their alfalfa stands. Only 14 percent applied small amounts of potassium. Nine percent applied manure and just over one-third of farmers used nitrogen fertilizer, but most of this was applied to cover crops during the establishment year.
Soil and plant tissue samples were taken and analyzed in the study, but the practice pointed out another deficiency.
Fertilizer recommendation limits were developed in Alberta under mostly dryland conditions. They aren’t reliable on high pH irrigation soils, McKenzie said. Therefore, tissue test values from the U.S. were used.
McKenzie said more research is needed to establish reliable methods for predicting phosphorus and potassium fertilizer responses.
However, the study did yield some general recommendations.
If soil and tissue phosphorus are low, significant increases in yield can be obtained from phosphorus fertilizer. Potassium fertilizers should give responses on sites where the soil potassium is marginal or low.
If the soil has a high pH value – above 7.8 – the Kelowna methods of analysis for soil phosphorus appear to be more reliable than the traditional Miller Axley method.
– Alberta Agriculture
Sarafloxacin approved for poultry
WASHINGTON, D.C. (Reuter) – The United States Food and Drug Administration has approved the antibiotic sarafloxacin for use in poultry drinking water to control illnesses caused by E. coli bacteria.
It is the first antibiotic made from fluorquinolone to be approved for use in food animals, the FDA said. FDA commissioner David Kessler warned the antibiotic must be used appropriately.
“It is important that antibiotics for food animals be used correctly to minimize the potential for development of drug-resistant microbes,” he said.
