Placement Drill - A machine which places fertilizer close to the side of rows of seeds and slightly below them. Fertilizer placement improves the efficiency of usage by ensuring the nutrients and concentrated close to actively growing roots in young seedlings.

Plague - Infectious disease caused by Pasteurella pestis. It is basically a disease of rodents which is transmitted to man and livestock. Plague is characterized by high fever, prostration, pneumonia, hemorrhage from the mucous membranes and toxemia.

Planker - An implement used to crush clods on land where a roller cannot be used, consisting of a number of fixed overlapping planks, shod with iron bars along the working edges, which is pulled over the lands. Also called float, rubber or scrubber.

Plant Breeding - Applied branch of botany dealing with the crop , improvement and production of new improved crop varieties far better than original in all aspects.

Plant Consumption - Water used by vegetation in the process of growth, including that stored in the body of the plant and that dissipated from its leaf and body surfaces by transpiration.

Plant Food Ratio - The ratio of nitrogen to phosphate and potash in a fertilizer. Thus a compound fertilizer containing 20% N, 10% P, and 10% K has a ratioof2:1:1. Such ratios are a guide to the type of compound. A number of fertilizers may have same ratio and therefore be usable for the same purpose, but the quantity needing to be applied will vary in relation to the actual percent age nutrient content.

Plant Louse - Aphid.

Plashing - Layering.

Plat - A plot of ground.

Plate Mill - A machine which coarse grinds grain, consisting of two circular plates of equal diameter positioned one above the other, with an adjustable gap between them to control the fineness of grinding. The lower plate is fixed whilst the upper one rotates against it. Plate diameter varies between 15 and 45 cm (6-18 in.)

Platyhelminthes - Flatworms.

Pleaching - Layering.

Plough - One of the oldest types of tillage implement which breaks up the land, turning over the soil into ridges and furrows, burying surface vegetation and manure and exposing the new soil surface to the air in preparation for sowing seed. The earliest types were wooden and of simple design. The principal parts of modem ploughs comprise a steel frame to which are fixed a number of bodies, each consisting of a Coulter which cuts a vertical slice, and a Share which makes a horizontal cut under the furrow slice which is then turned. by the Moulboard. The lateral accuracy and stability of each body is maintained by a Landside. Three main categories of tractorsdrawn ploughs are in common use on farms, viz, (a) fully mounted types, attached to the three point linkage and raised or lowered hydraulically, ( b) semi mounted types, in which a rear wheel partially supports the weight, and (c) trailed types, pulled by a drawbar.

Plough Pan - Pan.

Plough-in - To bury a crop, stubble, weeds, etc., by turning them under the soil with a plough.

Ploughing- 1. Tilage operations carried out with the help of tractor drawn or bullock drawn implements known as plough, before the crops are sown.
2. Tillage operations carried out for preparing the seedbed of crops. Ploughing essentially means opening the upper crust of the soil, breaking the clods and making the soil suitable for growing seeds.

Ploughing Iron - A term for any of the iron parts of a plough, e.g., Coulter, Share, etc.

Ploughing Rate - This can be approximately calculated by the following formulae which assume a field efficiency factor of 70% to take account of headland turning and non productive time.
working width (m) - x speed (km/h)
Hectares per hour=                     14.28
                             working width (yds) -  speed (m.p.h)×
Acres per hour=    _____________________________ 3.93

Ploughland - 1. Arable land.
2. The amount of land that could be tilled in a year by a plough drawn by a team of eight oxen, together with a proportionate amount of pasture, used historially as a basis for determining taxes.

Plough Sole Placement - Method of fertilizer application in which fertilizer is placed in a continuous band on the bottom of the furrow in the process of ploughing. Each band is covered as the next furrow is turned, usually during the growing season.

Pneumatic Separator - Seed processing machine in which seed separation is made by air on the basis of differences in terminal velocity. It has a fan at the intake end and a pressure greater than the normal atmospheric pressure is builtup within the machine. The air blast is responsible for seed separation.

Plucker Finger - A wire loop in a hop picking machine which severes the cones from the Bine.

Poaching - The trampling of land when wet, mainly by cattle, so that the soil becomes churned and muddy. Poaching is a particular problem of heavy land, and leads to the deterioration of soil structure.

Pocket - 1. An elongate sack into which hops are ressed, about 2 m (6 1/2 ft) tall and 60 cm (2 ft) in diameter. Also the quantity of hops contained in such a sack, about 76-89 kg (1½ - 1¼ cwt). 2. A measure of wool equal to 76 kg (168ibs).

Podsol - A type of soil in which minerals have been leached from the surface layer and deposited in the subsoil, often forming a hard pan impenetrable by roots. The upper leached layer is usually extremely poor in mineral salts and consists of bleached sand. It is often covered with very acid, decomposing plant material. Such soils are common on quick draining sandy heaths, and under conifer forest, particularly in the cool, wet areas.

Point - A share or tine.

Point of Lay - The state of a pullet when about to lay its first egg.

Points - The important features or body characteristics of animals which are considered when judging livestock.

Poke - A loosely woven sack for green hops, able to contain 8-10 Bushels (0.29-0.36 cubic m). Also called greenbag, greensack.

Pole - An old measure of length equal to 5 ½ yds (4.6 m), or ofarea equal to 30 ¼ sq. yds (25.3 sq. m.). Also called rod or perch.

Poll - 1. The top of the head. 2. To dehorn an animal. 3. To cut off the top of a tree.

Pollard - 1. An animal from which the horns have been removed. 2. A tree having had its crown cut off, and with new branches growing from the top of the stem.

Pollards - A term once given to a category of offal from wheat milling, consisting of fine bran and other products. All wheat offals, apart from bran, are now sold as weatings, and are used as a Feedingstuff.

Polled - A descriptive term for animals naturally lacking horns. Pollinator. A tree planted in an Orchard to provide Pollen for the fertilization of surrounding trees. Pollinators are usually of a different variety to the rest of the trees in the orchard.

Pooking Fork - A fork bearing three tines, used to push corn swaths together into sheaves for tying.

Pore Space - The space not occupied by soil particles in the soil.

Pot Ale - A syrupy residue (Syrup Feeds) from the first distilling process of whisky which, is now being used by stock fanners as a supplement to complement low quality roughage, such as straw, or low quality hay. The syrup is a good source ofenergy and protein and also contains substantial amounts ofphosphorous, potassium and copper. It has an M.E.. content ofdry matter higher than that ofbarley. Methods offeeding the syrup vary from inclusion in complete diets or pouring directly over roughage along feed troughs, to self feeding from open containers. Ball feeders are generally unsatisfactory due to the syrup's viscosity, except when the dry matter content is low.

Potash - A term applied to potassium carbonate (K₂CO₃), potassium hydroxide (KOH), potassium oxide (K₂O), and to potassium. salts in general.

Potash Fertilizers - Fertilizer.

Potash Nitrate - A fertilizer containing about 15% Nitrogen and 10% Potash, derived from natural deposits in Chile, and mainly used in market gardening as a top dressing.

Potassium - (K). A metallic element found naturally in various salts and present in the soil in Clay Minerals. It is essential to life, influencing both Carbohydrate and Protein metabolism, and the movement and utilisation of water in living organisms. In plants it ensures healthy growth, improving both resistance to drought and fungal disease, and winter hardness. It assists in the transportation ofthe products ofphotosynthesis and counteracts the effects ofexcessive applications ofnitrogen. In animals, it contributes to the maintenance ofthe osmotic balance ofthe body fluids, particularly intracellular fluid, and influences muscular and nerve activity. Continuous cropping, lack ofmanuring, excessive dressings ofnitrogen, and certain crops with a high potassium requirement (e.g. mangolds, lucerne, potatoes, sugarbeet, etc.) may deplete the soil ofpotassium. It may also be deficient in sandy, peaty or chalk soils. It is applied in the form ofvarious potash fertilizers.

Potato - A perennial herb (Solanum tuberosum) grown for its Carbohydrate rich edible tuber, mainly for human consumption. Characterised by compound pinnate leaves with large and small leaflets in alternate pairs.