Grain Amaranth (Amaranthus spp.)

This crop was identified as possibly having some potential for the southern areas of New Zealand by Mr Wayne Hutchinson, who attended a New Crops Conference in Atlanta in 2002. A quick search across a number of Internet sites came up with the following information. It is important to note that Crops for Southland does not have any experience with this crop and does not know if it can be grown successfully here.

People from diverse countries such as Mexico to Nepal have been using Grain Amaranth for centuries. Because it is easy to digest, Amaranth is traditionally given to those who are recovering from an illness or a fasting period. Amaranth is a C4 plant that germinates quickly when soil temperatures reach 15°C to 18°C. Seeding rate should be increased to compensate for lower emergence rates when soil temperatures are less than 15°C. This may make growth in Southland marginal. No-till methods have been attempted in Minnesota to minimise damage to seedlings from blowing soil particles. Amaranth was planted in oat and alfalfa stubble killed with glyphosate prior to planting. Emergence was slower than in conventionally tilled soil, possibly because of lower soil temperatures.

Farmers grow amaranth as a row crop to allow weed control by cultivation. A few growers have grown amaranth successfully in 25 cm row spacing. However, weeds can become a serious problem with narrow row spacing if soil surface moisture promotes weed germination at the time of planting. At present, all available post emergence broad-leaf herbicides are phytotoxic to the crop.

There is only limited and preliminary information available on the fertility requirements of amaranth. In a study in Arkansas, one line of A. cruentus L. and one line of A. hypochondriacus L., were grown at three N rates (0, 100, and 200 kg/ha). A two-fold yield increase was reported at the N rate of 100 kg/ha. No yield advantage was noted at the higher N rate. In a second year, there was no response to N.

Observations in many test plots and farmers' fields suggest that grain amaranth is drought tolerant at later stages of growth. Residual soil moisture is needed to assure that emergence occurs. Researchers in China have reported that the water requirement for growing grain amaranth is 42–47% that of wheat, 51–62% that of maize. To date, insect and disease problems of economic importance have been minimal. Yields of grain amaranth are highly variable and depend on many factors.

Weather patterns play a particularly important role in achieving a good plant stand to maximise yield. An autumn weather pattern consisting of a light frost followed by a period of mild weather can account for significant yield losses due to shattering. In some regions, a light frost partially dries the head but fails to penetrate the crop canopy and dry the entire plant sufficiently to permit harvest. Recovered yields in farmers' fields have ranged from 100 kg/ha to as high as 1500 kg/ha. Hand harvested yields have been as high as 4000 kg/ha in Montana and 6000 kg/ha in Peru.

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