Cultivation of Potato

The Potato belongs to the family Solanaceae. There are many related species, but only the potato and a few others bear tubers. Potatoes are an important staple food crop. Annual world production of potatoes surpasses that of all other vegetables and ranks with wheat and rice. Introduced into Europe in the 16th century by Spanish explorers, it is cultivated throughout the world including the Indo-Pakistan subcontinent. Potatoes are used alone and mixed with meat, fish, chicken, and vegetables, & in big cities and towns, potato chips are prepared and sold commercially. The potato is rich in starch and contains protein, minerals, & a fair amount of vitamins, particularly Vitamin - C. The potato has a wide range of seasonal adaptability. It is a cool season crop and is moderately frost - tolerant Temperature during the growing season has long been recognized as one of the most important factors influencing yield. Young plants grow best at a temperature of 240C; later growth is favored at 180C. Tuber production reaches a maximum at 200C, decreases with rise in temperature, and at about 300C tuber production stops entirely. Short days are beneficial for tuber production. The potato develops best on deep, fertile, sandy lo clay loams with good water retention capacity. Because the potato has a relatively weak, shallow root system, impermeable layers in the soil limit rooting depth, which restricts water availability to the plant in dry periods. Thus soil compaction can greatly reduce potato yields. Aeration of the soil has a great effect on the set and development of tubers. Potatoes need frequent irrigation. The first irrigation should be given immediately after sowing, and thereafter at one week intervals. After tuber formation, the frequency of irrigation is decreased. Care must be taken while irrigating that the water does not reach fee top of the ridge. Irrigation should be stopped a few days before harvesting. The size of the tuber increases until the vines become dry. In developed countries, potatoes are harvested by mechanical harvesters. In Pakistan, they are manually harvested by digging up the ridges with a spade.  Care must be taken that tubers are not injured during the process. After harvesting, the crop should be kept in the shade.

 

Text №11 Nitrogen fertilizers

In March of 1910, the German chemist Fritz Haber synthesized ammonia from osmium, nitrogen and hydrogen gases. This discovery led to the birth of nitrogen fertilizers. Nitrogen fertilizers use on vast areas of croplands started hence. Food production increased as the world's population boomed from 1 billion to 6 billion in the 20th century alone. Although global food security is indebted to nitrogen fertilizer, its excessive use has contributed to the increase of greenhouse gases in the atmosphere as well as water pollution. Plants are actually unable to process at least half of the amount of nitrogen fertilizers that farmers apply. The extra substances dissipate into the air and trickle off into the soil and bodies of water. Along with nitrogen fertilizers, phosphorus fertilizers are starters. The advantage of phosphorus fertilizer over the other type is that it has mineral properties. Because of these characteristics, it does not run off as easily or break down as quickly as nitrogen. Phosphorus fertilizer is best applied around the soil before planting the wheat seed. Furthermore, the application must anticipate the growth path of roots. For already grown plants, crop producers apply the fertilizer as close to the roots as possible. Plants cannot consume all the nutrients from phosphorus fertilizers and even a single use of it can benefit as many as eight crop plantings. Wheat plants, like other crops, require sizeable amounts of potassium to make starch to store energy and aid in photosynthesis. Like the phosphorus type, potassium fertilizers need to be applied close to the roots or the areas where the roots are projected to grow. Potassium fertilizers differ from phosphorus fertilizers in the rate of use. Since crops will utilize potassium regardless of the plants' needs, wheat growers should stagger the application of these fertilizers throughout the wheat growth phase. This measure will increase nutrient efficiency and promote less wastage. For wheat, farmers use potassium chloride because it has more potassium content than potassium nitrate.

TEXT№ 12 Sprinkler irrigation

Sprinkler irrigation is a method of applying irrigation water which is similar to natural rainfall. Water is distributed through a system of pipes usually by pumping. It is then sprayed into the air through sprinklers so that it breaks up into small water drops which fall to the ground. The pump supply system, sprinklers and operating conditions must be designed to enable a uniform application of water.

Sprinkler irrigation is suited for most row, field and tree crops and water can be sprayed over or under the crop canopy. However, large sprinklers are not recommended for irrigation of delicate crops such as lettuce because the large water drops produced by the sprinklers may damage the crop.

Sprinkler irrigation is adaptable to any farmable slope, whether uniform or undulating. The lateral pipes supplying water to the sprinklers should always be laid out along the land contour whenever possible. This will minimize the pressure changes at the sprinklers and provide a uniform irrigation.

Sprinklers are best suited to sandy soils with high infiltration rates although they are adaptable to most soils. The average application rate from the sprinklers (in mm/hour) is always chosen to be less than the basic infiltration rate of the soil (see Annex 2) so that surface ponding and runoff can be avoided.

Sprinklers are not suitable for soils which easily form a crust. If sprinkler irrigation is the only method available, then light fine sprays should be used. The larger sprinklers producing larger water droplets are to be avoided.

A good clean supply of water, free of suspended sediments, is required to avoid problems of sprinkler nozzle blockage and spoiling the crop by coating it with sediment.

Sprinklers provide efficient coverage for small to large areas and are suitable for use on all types of properties. It is also adaptable to nearly all irrigable soils since sprinklers are available in a wide range of discharge capacity.

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