Cereal yield

Scientific trials involving applications of animal manure were implemented as early as the 1930s, e.g. in Nigeria. Experimental rates of application have varied from 2 to 5 t to as much as 60 t ha 1 (Swift et al., 1994 Nandwa and Bekunda, 1998 Schlecht et al., 2006). Yield effects have throughout been positive, both in short-and long-term experiments sometimes severalfold increases in cereal yields were obtained (Pieri, 1992 Swift et al., 1994 Bekunda et al., 1997 Bationo et al., 1998 Nandwa and Bekunda, 1998). 

Fig. 24.2. Growth of cereal yield and area in cereal production in South Asia and Sub-Saharan Africa between 1961 and 2001 (1961 = 100 for yield and area).

Organic farming can contribute significantly to surplus reduction since the observed yields are much lower in organic as compared to conventional production. This is particularly true of plant production (Offermann and Nieberg 2000). For example, cereal yields in organic production are... 

Doyle, R. J., Parkin, R. J., Smith, J. A. C., and Gartrell, J. W. (1965). Molybdenum increases cereal yields on wheatbelt scrubplain. J. Dept. Agric. West Aust. 6 699-703. 

Due to the sensitive implications of expansion of agricultural areas (considerable investment and lower average yields, while possibly incurring social and environmental costs), the alternative to increasing global food production is to further increase land productivity. From the 1960s on, global cereal yields have continually increased. 

The production projections are made by estimating net and gross cumulative investment for the projected period to allow assessment of the macroeconomic proportions. The gross value of crops is calculated and inputs are analyzed. The crop production growth is estimated by assessment of the sources of growth such as yield per hectare, arable land growth, and cropping intensity. This produces projected crops and, in particular, cereal yield per hectare. 

A wide range of crops can be grown, but yields are very dependent on a good supply of water and adequate plant food. Cereal yields are usually low. Market gardening is often carried out where a good sandy area is situated near a large population. 

Cereal yield reductions are very high from wild oats as they are one of the most competitive grass weeds. Premiums can be lost for seed, malting and bread-making. The presence of wild oats on a farm may even incur a high dilapidations claim at the end of a tenancy. 

Key words cereal identification, grain quality in cereals, cereal growth, cereal yields,... 

A hydrolyzed cereal soHd, predominately a hexasaccharide, is used in high pH lime muds for reducing the yield point and gel strength (67). This additive has been used in systems treated with both sodium hydroxide and potassium hydroxide in addition to other additives common to lime muds (68). A second viscosity-reducing additive used in lime muds is a graft copolymer of acryflc acid and calcium flgnosulfonate (69). Both of these materials are used at levels of 6—17 kg/m (2—6 lb /bbl). 

The largest class of processes appHed to farm commodities are separations, which are usually based on some physical property such as density, particle size, or solubiHty. For example, the milling process for cereal grains involves size reduction (qv) foUowed by screening to yield products that have varied concentrations of starch, fiber, and protein. Milling of water slurries is practiced to obtain finer separation of starch, fiber, protein, and oil. 

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. 

Austin, R.B. (1987). Some crop characteristics of wheat and their influences on yield and water use. In Drought Tolerance in Winter Cereals, ed. J.P. Srivastava, E. Porceddu, E. Acevedo and S. Varma, pp. 321-36. Chichester John Wiley. 

Some modern varieties of cereals such as wheat and rice achieve high yield potential through genetic factors for plant dwarfness that improve harvest index. A popular notion among plant breeders is that high-yielding... 

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. 

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