Barley crop yield

A sound crop rotational system is of basic importance to the organic farmer. It reduces the risk of diseases and pests associated with monoculture, gives better control of weeds, spreads the labour requirements more evenly over the year, reduces the financial risk if one crop yields or sells badly and provides more interest for the farmer. For instance, take-all is a disease that cannot even be controlled chemically. Winter crops are more susceptible to take-all than spring sown crops and wheat is more susceptible than barley, so the safest position for winter wheat is immediately after a break crop. 

Figure 6.1 is a plot of relative crop yield versus soil salinity, and shows the regions for classifying crops based on their salinity tolerance. The crop yield for barley is indicated by the dashed line, with its crop yield indicating that it is tolerant to soil salinity. 

Fig. 6.1 Classifications of crop tolerance based on relative crop yield versus soil salinity. The tolerance of barley is shown by the dashed line. Adapted from Maas (1985) and Maas and Hoffman (1977)...

Research into the effects of air pollutants on plant growth and metabolism has moved towards the study of plant responses to low levels of pollutants ("chronic injury") and the interactions with environmental conditions. Plant growth and crop yield are known to be affected after exposure for long periods to low pollutant levels (1). For example, exposure to SO2 and NOx resulted in increased leafiness and reductions in root growth (2,3,4), while in barley overwinter reductions in crop growth have been reported (5,6). These effects on plant growth have been related to photosynthesis and the distribution of photoassimilate, the processes that sustain dry matter production in plants (7). 

Many crop yields have significantly increased since the 1960s. Wheat and barley yielded similarly in 1966 at around 4 tonnes/hectare (t/ha). Yields increased steadily right up to the late 1990s with most improvement in the yield of wheat. Since the late 1990s yields have plateaued (Fig. 0.3) despite improvements in varieties and crop husbandry and a small increase in atmospheric carbon dioxide. 

Copper exhibits rhizotoxicity in wheat seedlings [17]. Copper and chromium retard shoot and root growth of barley [18]. The yield of wheat is decreased when soil is contaminated with cadmium oxide or zinc oxide [19]. Copper and nickel smelter-polluted soil retards biomass growth of pine trees and reduces the essential calcium, potassium, and magnesium contents of sapUngs [20]. Cadmium in the soil reduces ryegrass growth with crop yields inversely proportional to cadmium content [21]. 

Plant and Animal Nutrient. Copper is one of seven micronutrients that has been identified as essential to the proper growth of plants (87). Cereal crops are by far the most affected by copper deficiency (see Wheat and other cereal grains). Greenhouse studies have shown yield increases from 38% to over 500% for wheat, barley, and oats (88) using copper supplementation. A tenfold increase in the yield of oats was reported in France (89). Symptoms of copper deficiency vary depending on species, but often it is accompanied by withering or chlorosis in the leaves that is not ammenable to iron supplementation. In high concentrations, particularly in low pH sods, copper can be toxic to plants. 

Grumet, R., Albrechtson, R.S. Hanson, A.D. (1987). Growth and yield of barley isopopulations differing in solute potential. Crop Science, 27, 991-5. 

Winter barley is an ideal entry for oilseed rape because the earlier harvest allows early drilling of rape. It has been shown on organic farms that building up fertility by using a green manure crop, such as red clover, has paid off financially, with the subsequent boost in yield of the following cereal crop. 

A ready reckoner for the amount of N, P and K removed by certain representative crops is shown in Table 5.2. The requirement for P and K may be expressed in terms of the element rather than the oxide (P205 or K20). P205 contains 0.43 units of P K20 contains 0.83 units of K. The depletion of N, P and K from the grain of wheat, barley and oats is pro rata for yield, but the nutrient composition of the straw is different, oat straw containing very much more potassium than wheat or barley straw. Potatoes and kale are very much more exhaustive of N and K than the cereal crops. 

The commonest type is a mixture of barley and oats. The yield of grain is usually better than if either crop was grown alone, but care must be taken to choose varieties which ripen at the same time. 

Wheat, barley Protein stability during storage, low producer price Food crops, lower yields, more difficult to transform and manipulate... 

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