Principles of Crop Science: Introduction

• AC12 Principles of Crop Science

What is Agriculture?

• Agriculture comes from the Latin words "ager" (land or field) and "cultura" (cultivation).
• It is the science of producing crops and livestock using the earth's natural resources.
• The primary goal of agriculture is to maximize land productivity while safeguarding against deterioration and misuse.

What is Crop Production?

• It deals with the production of food, fodder, fiber, sugar, and oilseed crops.
• It integrates agronomy, soil science, entomology, pathology, and microbiology.
• The aim is to improve food production and disease control.

Crop Science Branches

• Crop Improvement includes plant breeding, genetics, and bio-technology.
• Crop Management includes agronomy, soil science, agricultural chemistry, seed technology, agricultural microbiology, crop physiology, agricultural engineering, environmental sciences, and agricultural meteorology.
• Crop Protection includes agricultural entomology, plant pathology, and nematology.

Early Crop Domestication

• Hunting and Gathering: a Paleolithic practice.
• Shifting Agriculture: a Neolithic practice from around 7,000 BC.
• Medieval Agriculture: practiced from 500-1450 AD.
• Livestock farming: began in the 18th century.
• Fertilizer/Pesticide use: introduced in the 20th century.

Shifting Cultivation of Crops

• It is a primitive agricultural method involving forest clearing and burning to create garden sites.
• After a few years, when the soil becomes infertile or infested, farmers move to new locations.
• It is also called the Assartage system, where crops are cultivated until the land is exhausted.
• This is contrary to the fallow system, where land is rested without crops.

Subsidiary Cropping

• It is an undeveloped system of settled farming, involving cultivation, gathering, and hunting.
• People started settling near streams or rivers as permanent village sites, cultivating the same land continuously.
• Tools, crops, and cropping methods were primitive.

Survival Cropping

• It is an advanced form of primitive agriculture where agriculture is a way of life based on growing food for personal consumption.
• Crops are raised solely for family needs.

Mixed Cropping

• It consists of both crop and animal components.
• Field crop-grass husbandry was common, marking a shift from food gathering to food growing.

Advanced Farming

• Advanced practices involve crop and variety selection, seed selection, and green manuring with legumes.
• Other practices include crop rotation, use of animal and crop waste as manure, irrigation, and pasture management.
• It also involves raising animals like bullocks, sheep, and goats and stall feeding birds.

Scientific Agriculture (18th-19th Century)

• Modern agriculture began in the 18th century with crop sequences and organic recycling.
• It also included the introduction of exotic crops and animals, and the use of farm implements.
• Research and development in basic sciences were applied to agriculture in the 19th century, leading to its teaching as a science.
• Books, journals, and scientific articles were introduced, with new media and audio-visual aids spreading research findings to rural areas.

Modern Agriculture (21st Century)

• Today's agriculture is shifting from production-oriented to business-oriented.
• Developments in hydrological, mechanical, chemical, genetic, and technological aspects are in progress.
• Governments allocate national budgets for agricultural advancement.
• Small and marginal farmers get subsidized agricultural inputs.
• Policies on preserving, processing, pricing, marketing, distributing, consuming, exporting, and importing are being strengthened.

Laboratory 1: Community Available Crops

• Objectives include identifying local crops, discussing their management, identifying other suitable crops, and presenting findings.

Laboratory 2: Leaf Surface Area

• Materials needed include a laptop, ruler, fresh leaves (3-12 inches), camera with HD, and graphing paper.

Laboratory 3: Laying Out an Orchard

• Materials: 2 bamboo sticks per student (1m height, 1 inch width, ½ inch thickness), 1 pack plastic twine for the class.

Crop Classification

Botanical System

• Using systematics and taxonomy
• Developed by Carolus Linnaeus (1707-1778), who was a Swedish physician
• Each plant has a two-word name (Genus and Species) in Latin
• Systematics or Taxonomy is an organized system for descriptive classification of plants
• Nomenclature is a system of assigning names to plants

Latin Language in Botanical Classification

• Names reflect plant attributes or use:
  • Alba = white
  • Variegata = variegated
  • Rubra = red
  • Esculentus = edible
  • Sativum = cultivated

Functional System

• Agronomic crops: field crops, usually extensive in culture
• Horticultural crops: grown in small areas, intensive culture, and high value

Agronomic Crops

• Cereal or grain crops
• Grain legumes
• Fiber crops
• Root and tuber crops
• Forage crops
• Oil crops
• Sugar crops
• Alcohol crops
• Stimulant and drug crops

Special Purpose Classification

• Green manure crops
• Cover crops
• Catch crops/emergency crops
• Soilage or Soiling crops
• Silage crops
• Trap crop

Land Preparation

• Land: Manipulation of soil providing good physical, chemical, and biological conditions that permit optimum plant growth.
• Tillage: Mechanical manipulation of soil from a known to a desired condition.
• Soil Tilth: Physical condition of the soil as related to its ease of tillage.

Preparing Virgin Land

• Remove existing vegetation.
• Cut down trees and clear bushing, and remove obstacles.
• Modify the terrain by leveling or terracing.

Objectives of Tillage

• Develop a desirable soil structure for a seedbed for:
  • Higher water infiltration rate.
  • Decreased water surface runoff.
  • Greater water holding capacity.
• Control weeds, cut roots, and bury green materials.
• Incorporate manure and chemical fertilizer.
• For wetland conditions, turn the soil into a soft "puddle" and form a hard layer to reduce water leaching.

Classes of Tillage Operation

• Primary tillage: Initial cutting, breaking, and inversion of the soil using moldboard, disc, and chisel plows and subsoilers to a depth of 6"-36". Often referred to as plowing.
• Secondary tillage: Subsequent breaking, pulverization, and leveling of the soil to prepare it for planting using disc, spike-tooth, and spring-tooth harrows to a depth of 3"-6". Often referred to as harrowing.
• General-purpose tillage: Combined primary and secondary tillage in one operation using rotavators and floating tillers to a depth of up to 6". Often referred to as rotavating.

Tillage Systems

• Conventional Tillage
• Conservation Tillage

Planting Methods

• Direct Planting: Placing vegetative parts of crops that are vegetatively propagated, i.e., potato tubers, ginger/turmeric mother sets, sweet potato/grape cuttings, sugarcane sets.
• Transplanting: Raising seedlings on the nursery beds.
  • Seedlings are allowed to grow on nursery beds for about 3-5 weeks.
  • Beds are watered to prevent jerk to the roots.

Direct Seeding Methods

• Broad casting: Scattering seeds by hand over the field, then covering with a plank or harrow.
  • Used for crops like wheat, paddy, sesamum, methi, and coriander.

Advantages of Broad Casting

- Quickest & cheapest method.
- Does not require skilled labor or implements.
- Is followed in moist conditions.

Disadvantages of Broad Casting

- Requires more seed, crop stand is not uniform.
- Results in faulty germination where moisture is inadequate.
- Spacing is not maintained, making interculturing difficult.

• Drilling or Line sowing: It is the dropping of seeds into the soil. Uses the help of equipment such as mogha, seed drill, seed-cum-fertilizer driller. Seed is then covered by earth or plank or harrow.
  • Used for crops like Jowar, wheat Bajara.

Advantages of Drilling or LIne Sowing

- Seeds are placed at proper & uniform depths.
- Interculturing can be done along the rows.
- Uniform row to row spacing is maintained.
- Seed requirement is less than 'broad casting'.
- Sowing is done at proper moisture level.

• Dibbling: Placements of seeds at cross marks in the field. Requires help of machine.
  • Groundnut, Castor, and Hy. Cotton are examples of where its used

Advantages of Dibbling

• Involves the use of hand-held tools to dig a shallow hole in which seeds are placed and covered with soil.
• It is practical only for seeding small areas.

Mechanical Planting

• Mechanized seeding: Use of agricultural machinery for automatic sowing.
• Mechanical transplanting: Use of machinery for plating bare-root or rooted plants.

Mechanical Seeder Types

• Random Seeders:
  • Less precise and use gravity to distribute seeds.
  • Involves thinning seedlings to desired spacing.
• Precision Seeders:
  • Accurate metering for equidistant distribution at a specific depth.
  • Reduces costs by minimizing the need for thinning.

Transplanting Factors

• Factors to consider if the crop should be transplanted or dry seeded.
  • Rate of root regeneration.
  • Type of root system.
  • Days from seed to harvest.
  • Rate of seed germination and seedling growth.

Depth of Sowing

• Seed size
• Type of seedling emergence
• Soil type
• Depth of moisture of soil

Plant Arrangement

• Arrangement influenced by factors affecting plant density.
• Types of distribution includes random and Patterned: (Square, Hexagon, Quincunx, Triangular.)

Plant Density

• The number of established plants per unit land area.
• It should be estimated to optimize crop establishment.
• This avoids over or under seeding

Growth vs Development

• Growth is an irreversible increase in size (quantitative change).
• Development is qualitative change (e.g., initiation of leaves, roots, and flowers).

Plant Growth Analysis

• Analyzes set of quantitative methods that describe the functions of plant systems.
• Provides integrative approach to describe plant forms and functions.

Plant growth measurement

• Weight
• Leaf area
• Volume
• Length or Height

Plant dry weight

• The weight of a plant or its parts is oven-dried at 80°C for at least 48 hours.
• It helps measure of the actual dry matter.

Factors of Measurement:

• Portable Leaf Area Meter
• Digital Image Analysis
• Measurements of plant heigh and fruit volume

Leaf Area Index (LAI)

• Ratio of one-sided leaf area to ground area unitless index. LAI = (Leaf Area/ Ground Area)

Fertilizer Terminology

• Fertilizer: Substance added to soil/plant supplying essential nutrients
• Fertilizer grade: Guaranteed % of total nitrogen (N), available phosphorus (P2O5), and water-soluble potassium (K): e.g. 16-20-0.

Fertilizer

• Total plant food: Percentage of nutrients (N, P, K, S) in a fertilizer material.
• Carrier: Necessary material to hold the fertilizer element in a suitable form.
• Filler: Material added to provide the amount of nutrient per weight unit, make application easier, or reduce water absorption.
• Fertilizer recommendation: amount (kg) of N,P2O5, and K2O per hectare.

Fertilizer material classification

• According to form:
  • Natural organic: Undergone decomposition.
  • Commercial organic: Compost, chicken manure.
  • Chemical or inorganic: Natural/synthetic product of reaction.
  • Natural chemical: Rock phosphate, Chilean nitrate of soda.
  • Synthetic chemical: Ammonium sulfate/phosphate, superphosphate, complete fertilizer; urea.
• According to fertilizer elements present:
  • Single: contains only one of the 3 major fertilizer elements.
  • Incomplete: 2 of the 3 major elements. Example: ammonium phosphate(21-0-0)
  • Complete: all 3 major elements.
  • Mixed: Two or more major elements added by 2 or more fertilizer materials.

Common Fertilizers

• Complete fertilizer 14-14-14: 50 kg sack has: 14% nitrogen,14% phosphorus, and, 14% potassium.
• Ammonium phosphate 16-20-0: 50 kg sack has 16% nitrogen and 20% phosphorus