The introduction and use of oat (avena sativa) cultivars in pakistan
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- 7.7. Effect of harvesting/grazing on forage and grain yield
- Table 10a. Green-fodder yield (tons/ha) and gross income (Rs/ha) from oat cultivars at different cutting stages
- Table-10b. Seed yield (tonnes/ha), gross income from seed (Rs/ha), and gross income from fodder (F) + Seed (S) (Rs/ha) from oat cultivars under different cutting stages
In India, Taneja et al. (1981) found that with the application of 120 kg N/ha to the oats and barley crops, the green fodder and dry matter yields increased significantly. For seed yields, however, the significant response was observed up to 80 kg N/ha. Also the application of 80 kg N/ha provided the maximum net profit of Rs. 4022.30/ha. Available nitrogen is usually the limiting factor in dry matter production of winter forage (Crofts, 1966b), and oats and other small grain cereals have shown considerable increase in forage and grain yield due to nitrogen fertilization after grazing. The response will vary according to the temperature, soil type, soil fertility level, rotation system, irrigation, cultivar, date of sowing, time of nitrogen application and other environmental factors. In USA, Ohm (1976) recommended that more extensive testing of potential new cultivars be undertaken to determine specific fertility x cultivar interactions. It was found that application of nitrogen resulted in significant increases in plant height, lodging score, percent protein, and yield in oat cultivars; it did not affect heading date or seed weight; and it reduced test weight. Short-strawed types increased in plant height more with nitrogen application than several taller cultivars although plant height increases were greatest for other tall types. Lodging scores of weaker-strawed cultivars did not always increase more with nitrogen application than those of stronger-strawed cultivars. Percent protein in certain low protein cultivars increased more than that of some high protein cultivars with fertilizer nitrogen. A given cultivar may not respond similarly to nitrogen in terms of percent protein and/or yield. More extensive testing of potential new cultivars to determine specific fertility x cultivar interactions was recommended. In Australia, autumn sown oats has shown a large response in forage yield to nitrogen fertilization and irrigation, with economic benefits in reducing the winter-feed shortage (Crofts, 1966a, 1966b; Brown, 1975). Blackman (1936) showed that nitrogen can increase the growth rate of grasses when soil temperature at 10 cm is in the range of 5 -8 0C, as the slow release by bacteria of inorganic nitrogen from soil organic matter is limiting plant growth. Therefore, an application of nitrogen fertilizer after grazing a forage crop in winter should boost herbage production, make a second grazing possible or produce a substantial grain yield (Cook, 1971). Gill et al (1977) also found that application of nitrogen fertilizer up to 120 kg/ha increased fodder and crude protein contents. Oat crops can use the available nitrogen very effectively. In other circumstances, it helps in weed control and reduces the incidence of the fungal disease take-all in wheat a major root disease of wheat, caused by Gaeumannomyces graminis var. tritici. (Brown, 1975; Anon, 1984) Time of nitrogen application is also very important. Studies have revealed that the later the vegetative stage at which nitrogen is foliar-applied up to the bloom stage, the less is its effect on vegetative growth and the greater is its effect on grain protein. Foliar-applied nitrogen at or near heading has increased yield and percent protein (DeDatta et al., 1972, Sadaphal and Das, 1966, Seetanun and DeDatta 1973). Split application of nitrogen increased grain yield over single basal application in some cultivars by minimizing lodging (Seetanun and DeDatta 1973). Spratt (1974) suggested that NH4+N applied at the boot stage increased percent grain protein in wheat. Cultivars adequately or amply supplied with moisture have been shown to respond differently to nitrogen (N) application. Some cultivars (Gardner and Rathjen, 1975) produced maximum yield at natural fertility, others showed a typical parabolic response to increased nitrogen, and still others gave increased yields up to 275 kg N/ha. Additionally, cultivars with optima at 0, 70, and 275 Kg applied nitrogen/ha had similar yields (Gardner and Rathjen, 1975). Larger yield increases and smaller grain nitrogen concentration increases were obtained with a high yielding, low nitrogen (low protein) cultivar than with a low yielding, high nitrogen cultivar (MacLeod and MacLeod 1975). However, under dry-land conditions in semi-arid regions, wheat (Triticum spp.) cultivars of different heights did not respond differently for yield to nitrogen application (Bauer et al. 1965, McNeal et al. 1971). 7.7. Effect of harvesting/grazing on forage and grain yield: As little information was available on the economics of oat production in Pakistan, a study was undertaken on the economic aspects of oats harvested for fodder and fodder + seed at different harvesting intervals. Generally, farmers cut oats for fodder or grain alone but there is good scope to obtain both fodder and seed from the same crop. Hussain et al. (1994) evaluated five cultivars of oats for fodder yield, seed yield, and gross income at different harvesting intervals during 1987-89 at NARC, Islamabad (Table 10a). The cultivars ’PD2LV65’, ‘S-81’, and ‘Swan’ produced maximum forage yield (58.59, 54.99, and 54.58 tonnes/ha) and gross income (Rs. 14750, 13800, and 13720 when harvested only for fodder at 50 percent flowering stage. The highest seed yield (2.19 tonnes/ha) and gross income (Rs. 12380/ha) were obtained from PD2LV65 harvested only for seed (see Table 10b). Swan cut for fodder after 70 and 85 days of planting and then left for seed produced respectively 2.04 and 2.07 tonnes /ha seed yield and Rs. 11520 and 11590/ha gross income. The maximum cash income from fodder + seed was obtained from Swan harvested for fodder after 85 and 100 days (Rs. 18600 and 18980/ha) and PD2LV65 harvested 115 days after planting (Rs 18380/ha). Thus, It was also concluded that it was more economical to cut oats for fodder, 85-15 days after planting and then leave the regrowth for seed at maturity (Table 10b).
Table-10b. Seed yield (tonnes/ha), gross income from seed (Rs/ha), and gross income from fodder (F) + Seed (S) (Rs/ha) from oat cultivars under different cutting stages
LSD(P=0.01) Seed yield Gross income Gross income From F+S
In India, Taneja et al. (1981) found that oats and barley when planted early at the end of October provided one cut for green fodder without much reduction in seed yields from the same crop. The straw yields decreased significantly when one cut was obtained for forage while the seed yields remained unaffected. However, the straw yields of oats in general were higher compared to barley. Net income was invariably higher when the crop was harvested once for fodder. On the N.S.W. Tablelands, Dann et al. (1977) suggested that the most biologically profitable combination of herbage and grain production would be obtained by delaying grazing until about 4.0 tons of crop dry matter per hectare was available in winter. Subsequently, Dann et al. (1983) recommended that August (rather than earlier) was the best time for grazing oats. Wheeler (1981) suggested that further research was needed to quantify the effects of grazing on grain yield; in particular, if dual-purpose crops are to be used efficiently, farmers need in particular a means of estimating grain yield reductions in relation to duration and time of grazing. The effect of grazing a winter cereal crop on its subsequent grain yield has been investigated by numerous workers and depends on many factors. Grazing usually incurs a penalty by reducing grain yields, and typically a 20 percent reduction in grain yield can be expected if the crop is grazed once before stem elongation (Anon, 1984). However, experimental results have varied widely, as indicated below. Within a wide range of different climatic, environmental and agronomic conditions, some investigators have reported that “early” or “moderate” grazing or clipping of oats or other small grain cereals brought about an increase in grain yield or had no significant effect on it (Hubbard and Harper, 1949; Sprague, 1954; Holliday, 1956; Day et al., 1968; Mengersen, 1972; Dann et al., 1977; Skorda, 1977; Cannon et al. 1978; Fitzsimmons, 1978; Bishnoi, 1980; Craig and Potter, 1983; Davidson et al., 1985b; Sharrow and Motazedian, 1987; Winter and Thompson, 1987). By contrast, grain yields usually decrease in proportion to the lateness, number and severity of the grazing or clipping imposed on the crop (Hubbard and Harper, 1949; Holliday, 1956; Morris and Gardner, 1958; Pumphrey, 1970; Dann, 1971, Dann et al., 1983; Brown, 1975; Skorda, 1977; Fitzsimmons, 1978: Bishnoi, 1980; Dunphy et al., 1982, 1984; Winter and Thompson, 1987). Removing vegetation by either grazing or clipping has also reduced plant height, number of heads per m2 and straw production (Day et al., 1968, Pumphrey, 1970). Also delaying the time of clipping until late joint stage (Dunphy et al., 1982) gave reduced fertile tiller survival and fewer seeds per head, but had little effect on the average weight per seed. The higher grain yields following a single light to moderate winter grazing may have occurred as a consequence of some or all of the following:
On the other hand, the reduction in grain yield resulting from late spring and/or more severe grazing or cutting in different conditions might presumably be due to one or more of the following: - Removal of the main stem and primary tiller apices leaving grain yield to be carried on secondary, weaker tillers. - Reduction in the amount of growth made before flowering during unfavourable climatic Conditions such as high temperatures and long day lengths, leading to shorter maturity period, and possibly drought stress caused by increasing evapotranspiration rates (Hadjichristodoulou, 1983). - Reduction in top growth with a consequent adverse effect on root growth (Hadjichristodoulou, 1983; Cook, 1971) and increased incidence of root rot (Winter and Thompson, 1987). - Increased risk of frost injury if low temperatures prevail immediately after defoliation (Skorda, 1977). - Reduction in the supply of assimilates from the leaves caused by defoliation which may bring about a severe reduction of growth in the upper spike lets, increasing the proportion of shrivelled grain (Scott and Biscoe, 1980, unpublished report). In addition, the type of season may affect the grazing-grain relationship. Grazing has been reported to reduce grain yield more seriously in a dry cold season than a wet mild one (Dann, 1981). Sprague (1953) reported in a 4-year study with dairy cows that rye, wheat, and oats yielded forage in approximately a 3, 2, 1, relationship. Autumn and spring pasture production from rye was about 75 percent that from a Kentucky bluegrass white clover pasture on the same land from May to October. Grain production increased by autumn grazing and decreased by spring grazing. This increase was much more pronounced in seasons of cool temperature and adequate rainfall than during seasons which were hot and dry. Straw yields were much less after spring grazing but were unaffected by autumn grazing. No lodging occurred following spring grazing and less than 5 percent of the grains were lodged on plots autumn-grazed. There are many reports in the literature on the influence of temperature and management on yield of forage plants including small grains. Holt (1961) found that frequent clipping resulted in reduced plant development and reduced forage yields. A period of at least 4 to 6 weeks between clippings is necessary for recovery and regrowth. Height of clipping influences total plant development and rapidity of recovery following clipping, but not total yield of harvested forage. Weight losses in the crown area following mild defoliation generally are greater than with more severe defoliation, but recovery is more rapid. Klebesadel and Smith (1960) harvested oats at four stages of maturity and reported greater dry matter yields from a single harvest in the late milk to mature stages than from 2 to 3 harvests made earlier. Crowder et al. (1955) showed that winter forage yield of oats, ryegrass, and crimson clover was significantly related to the number of hours per growth period with temperatures above 450 F; and yields increased as the interval between clippings increased. Hadjichristodoulou (1976) reported that under moisture stress conditions, before and during the harvesting period, dry matter yields did not increase significantly with age. Protein content of cereals under low rainfall conditions was higher than that of cereals grown in the U.K. under higher N fertilization levels. Rainfall conditions affected drastically the performance of both cereals and legumes. However average yields were satisfactory. Directory: agp -> agpc agpc -> Reporting Officer agp -> Submitted by: g V pollard, slac-slcm date: 21 February 2006 II. Visit to Download 0.77 Mb. Share with your friends:
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