eChapters

Fertilizer

Fertilizers are defined as materials having definite chemical composition with a high analytical value that supply essential plant nutrients in available form. They are usually manufactured by industries and sold with a trade name. They are commonly synthetic in nature and also called as chemical fertilizers/inorganic fertilizers/commercial fertilizers other than lime and gypsum. Most of the chemical fertilizers are inorganic in nature.

Methods of fertilizer application

Two major methods are used to apply fertilizers  
I) Application of fertilizers in solid form 
II) Application of fertilizers in liquid forms

Fertilizer (Control) Order, 1985 which is administered by Deptt.of Agriculture Cooperation, Govt. of India has been issued under the Essential Commodities Act, 1955. The FCO lays, down as to what substances qualify for use as fertilizers in the soil, product-wise specifications, methods for sampling and analysis of fertilizers, procedure for obtaining license/registration as manufacture/dealer in fertilizers and conditions to be fulfilled for trading thereof, etc.

Use of biofertilizers in agriculture and their advantage
 
Bio-fertilizers or bio-inoculants

These are productions containing living organisms such as nitrogen fixers or phosphorus solubilises which are useful for agricultural production. Biofertilizers play a significant role in improving soil fertility and plant growth. By fixing atmospheric nitrogen both in association with plants and without plants solubilize insoluble soil phosphates into soluble phosphates there by increasing the availability of phosphorus secrete growth promoting substances and supplies to the inoculated plants.

Plant nutrients are naturally components of the soil orchestrated by weathering processes and that the abundance of these metals in our soil environment now-a-days is due to numerous anthropogenic activities. In the environment, heavy metals are partitioned among the various environmental compartments such as water, soil, suspended solids and biota. Processes such as dilution, dispersion, sedimentation, adsorption and desorption govern their distribution. They also exist in colloidal ionic particulate and dissolved phases,  have a high affinity for humic acids, organic colloids and oxides coated with organic matter. The soluble forms are generally ions or unionised organo metallic chelates or complexes. The solubility of metals in soil and groundwater is predominantly controlled by pH, amount of metal, cation exchange capacity, organic carbon content, the oxidation state of the mineral components and the redox potential of the system.

The requirement of micronutrients is always in low amounts while their moderate decrease causes the deficiency symptoms and a moderate increase causes toxicity. In other words, there is a narrow range of concentration at which the elements are optimum. Any mineral ion concentration in tissues that reduces the dry weight of tissues by about 10 per cent is considered toxic. Such critical concentrations vary widely among different micronutrients. The toxicity symptoms are difficult to identify. Toxicity levels for any element also vary for different plants. Many a times, excess of an element may inhibit the uptake of another element.

Toxic elements like Cadmium (Cd), Fluoride (F), heavy metals, radioactive metals are associated with mainly rock phosphates, other organic wastes like sewage sludge and pollutants. Their chemistry is similar to plant nutrients and replace them in their physiology leading to reduced uptake of nutrients, productivity and contaminated food chain.

Visit to a seed processing unit and attending the following questionnaire to know firsthand information on operations of shop floor

1.1 Problem
    1.    Compare the seed quality at different physiological maturity stages
    2.    Compare the seed recovery in acid and fermentation method

1.2 Materials
    ·    Tomato fruits – 4 batches
    ·    Plastic bucket/ Beaker
    ·    Water

Seed processing is specialized activity and also a tool to improve seed quality further to an acceptable standard. Seed quality parameters like germination, vigour or genetic purity can be improved using processing. Say a seed lot having a minimum standard of 90% germination, but the competition in the market offering seed quality 92 or 95 % then to meet the market demand we can process the seed lots using re-milling or re-conditioning techniques. Also sometimes simple techniques like liquid density separation which uses specific density of the seed to separate good seed from inferior quality can be considered.

The physical properties of seeds are a basic activity for designing processing equipments and precision planters. Since these characters vary with crop or variety, one needs to have the data handy to be used on shop floor. This data also helps to quantify processing efficiency, presence of dormancy and suitability for seed treatments for all existing and new crops or varieties.

Methods in Seed Blending

For good seed blending there are three methods and details of which given as below:

Mechanical damage is inflicted on seeds during harvesting, threshing drying, processing and handling. Injury may occur from any kind of physical abuse. Threshing abuse probably is most serious but, seed conditioning and handling also contribute to seed injury. High temperatures during drying or drying too quick or excessively can cause injury. Susceptibility to mechanical injury increases as the moisture content of the seed decreases. Effect of all individual impacts received by the seed appears to be cumulative in total seed damage. Cereals are largely immune to mechanical injury presumably because of the protective outer structures, the palea and lemma. Large sized legumes are more suscepitable. Small seeds tend to escape injury during harvest and seeds that are spherical tend to suffer less damage than elongated or irregularly shaped ones.

The processing operations are carried out based on the principle of physical differences found in a seed lot.

9.1 Magnetic seed separator

These machines use a magnetic force to separate damaged seeds or other particles from the good seeds. This is used to solve special problems in seed lots that can not be taken out with our other basic seed cleaning equipment. Most of the time it is used for vegetable and field seeds that have problems in seed damage (fish mouth in cucumber or melon seeds / cracked radish or cabbage seeds), insect damage (beetle holes in cotton seeds) or contamination with soil or plant parts (white plant parts in onion seed) etc.

Seed size is an important parameter of seed vigor as it in influences the performance of seed in soil. Seed bulk at harvest contains a wide range of seed sizes but these may not all be of equal value for sowing. Farmers have always realized the necessary of using uniform seeds for good viability to obtain high emergence and growth. This will also help in getting optimum plant population and higher yields.
 
The influence of seed size on seedling vigor and crop productivity has already been proven since the days Hannaford who was considered as father of seed processing. To achieve uniformity in seed size this optimum sieve/screen size is very critical for optimum seed recovery and economical seed yield. Though the screen sizes are standardized for different crops but vary with different varieties. The shop floor should continuously explore and fine tune screen sizes for different varieties.

This practical in continuation of the practical no.10 explore the effects of screen sizes on different varieties. The screen sizes vary not with crops but with varieties also. To know the effect of screen sizes among the varieties we need to take the top and middle screens as standard or as recommended. These methods can be applied to any crop and to different varieties.

The use of seed processing equipments helps in improving the seed quality by inducing uniformity of physical properties of seeds. This help in achieving optimum plant population and desired economic yield. In certain crops like soya bean, standard seed processing may not give desired seed quality because of sensitivity towards moisture. As general practice seed need to be dried to its safe moisture content of 9 before processing. But in case of soya bean lower seed moisture may result higher mechanical damage after standard seed processing. Drier seed are more vulnerable for mechanical damage. In this practical w try to explore the importance of moisture in seed processing and also need of alternative processing equipments like spiral graders to minimize mechanical damage.

Drying is an important unit operation in seed processing in order to maintain seed ability and vigor . it is advocated that seeds should be harvested soon after they attain physiological maturity to obtain better quality seeds and to minimize field losses. The traditional method of sun drying is inadequate, uncontrolled and time bound, which may not meet the high demand of quality seeds in time. Hence artificial drying, the effect of certain drying parameters like seed moisture content, drying air temperature, airflow rate, depth of seed loading and time of exposure on drying characteristics and viability of seeds are to be determined for safe and economical drying of seeds.

Objective: To study the seed treatment methods and equipments A key factor in achieving the few potential of good quality seed is the blanket treatment of the seeds with agrochemical in order to control or prevent diseases in the  crops.

Seed is the primary and essential starting point of a wide range of crops, including the majority of vegetables except those vegetative propagated (e.g- potato and sweet potato). Seedling emergence and field stand establishment is one of the problems facing the growers, especially in early planting where adverse conditions are prevailed (low temperature and high soil moisture). Seed germination and seedling emergence are affected by many factors such as: seed genotype, seed quality (seed viability and seed vigor) and the environmental conditions (moisture and temperature) prevailing during seed germination and subsequent seedling emergence, assuming that the seed is not dormant.

Seed Priming is the process of controlled hydration of seeds to a level that permits pre-germinative metabolic actively to proceed, but prevents actual emergence of the radical. It is done to increase the speed and uniformity of germination particularly under adverse conditions of temperature, moisture and salinity conditions. In this condition, seeds go through all the essential preparatory processes of germination but prevent cell elongation and radical emergence. During the waiting period at the osmotic barrier the ‘slower’ seeds tend to catch up with the ‘faster ones’ so that the subsequent germination is more uniform, than that of untreated seeds. The duration of priming varies with the crop as well as method of priming such that priming is allowed for I and II stage of seed imbibitions without allowing radical protrusion.

Objective

    1.    Design drum priming (2-3 kg and drying unit with house hold or commonly available materials.
    2.    Standardization of time for seed priming for different crops.

Probable drum priming unit components

A] A vertical drum which need to be rotating
B] A motor which will rotate
C] A desktop assembly
D] A simple two way seed drier (Fig not given here)

The objective of seed pelleting is to provide an opportunity to package effective quantities of materials such that they can influence the micro-environment of each seed.
 
Process of Pelleting

Seeds are introduced into a coating drum or pan that resembles a cement mixer. An amalgam of pelleting materials (clays, limestone, calcium carbonate, talc, vermiculite) and cementing adhesives (gum Arabic, gelatine, methyl cellulose polyvinyl alchol) are used to form the pellet and other compounds such as inoculants, fungicides, etc. May be added to enhance seed performance.

These materials include barrier coated paper bags, barrier laminated film bags, jute bags, PP woven box bag and cotton bags.
 
A: Paper Bags
    1.    Coated paper:  bags provide a barrier for leaking or staining of the product. This can be done by a greaseproof or claycoated kraftpaper.
    2.    Open-Mouth sacks:  can be manufactured using different types of paper. Simple kraftliner, glossy claycoated and lacquered outerliner are possible. These sacks can be supplied with liners and printed up to 8 colours.

Fumigation is a method of pest control that completely fills an area with gaseous pesticides to suffocate or poison the pests within. It is utilized for control of pests in buildings, soil, seed, and grain produce. It is also used during processing of goods to be imported or exported in order to prevent transfer of exotic organisms. Fumigants are chemical compounds in gaseous form that enter the body of insect through the spiracles spread all over via trachea and tracheoles. The important fumigants are Methyl bromide, Ethylene dibromide, Aluminium phosphide, Ethyl formate, Hydrogen cyanide, Chloropicrin etc.

The moisture content is the amount of water in the seed and is usually expressed as a percentage. It can he expressed on either a wet weight basis (where it is expressed as a percentage of the fresh weight of the seed) or on a dry weight basis (where it is expressed as a percentage of the dry weight of the seed). The seed moisture content is the most vital parameter, which influence the seed quality and storage life of the seed. Seed moisture content is closely associated with several aspects of physiological seed quality. For example, it is related to seed maturity, optimum harvest time, mechanical damage, economics of artificial seed drying, seed longevity and insect & pathogen infestation.

Mechanical damage in oil seeds like soya bean can be induced at any time during harvesting, handling, conditioning and sowing operations. There is relationship between moisture and mechanical damage. In general the low moisture containing seeds are more prone for mechanical damage than the high moisture containing seeds. In this experiment we look for this relationship by measuring seed quality parameters like germination and leakage (electrical conductivity).

According to Harrington’s rule (1960) of thumb, for storage, every one percent increase in moisture content, the seed life is halved far seeds of moisture content of 5-14%. For temperature, every 5^ºC rise in temperature, between 0-50 ^ºC, the seed life is halved.

Seed processing efficiency (SPE) is one of the important aspects in seed processing. It will help in measuring the potential of the shop floor. It will also help in standardizing activities like screens and improving physical purity. SPE will help to improve the quality of the seed material and help in utilizing the machines at their optimum capacity. SPE may vary among the different crops and even among the varieties.
 
To quantify SPE we need to pass the test sample (bulk-pre processed) through the target machine and enter the details in a processing register. To quantify the SPE we need to follow these mathematical formulae:

NAME OF THE UNIT: 

    1.    Location of Seed Storage 
    2.    Date of Inspections/visit

PPEs are the personal protection equipments which protect the personnel against some hazards in the shop floor. PPEs form important aspects of Environment (safe disposal of treated chemicals, dusts coming out of processing), Safety (to seed storages) and Health (personnel) (ESH) strategy of any shop floor.

The “falling number” is a measurement used by plant breeders and grain quality specialists to determine the soundness of wheat, which is primarily influenced by the degree of sprouting in a grain sample. Hagberg Falling Number is the full name of this international standard of sprout measurement.  The term “falling numbers” refers to the amount of time it takes for the Hagberg steel ball in this sprout analysis tool to fall through a flour/water slurry that has been heated to release the starch from water. 

There are stages in seed supply chain where seed losses happen at harvesting and post harvest stage. These losses may occur due to higher moisture at harvest, due to harvesting methods, processing methods, at seed storage, during transport etc. Estimation of these losses is an important function of seed inventory management. Estimating seed losses help to improve processing and seed distribution efficiency. These simple statistical tools will help to measure quantitative post harvest seed losses. Seed testing can be used for measuring qualitative post harvest seed losses.

To assess the quality of the seed is necessary before it is shipped for packaging and made available to the farming community. To assess certain routine seed quality parameters which are statutory for labelling seed sampling and testing are very critical. Seed testing is not only a mandatory trade requirement but also decides the market potential of a particular product in the market and safeguard the brand image of the company. Seed sampling for labelling and other trade requirements is done at processing plant. The reliability of seed testing is depends on the accuracy with which the sample represents the lot and precision of the laboratory test. In many cases variations in the test results are due to variation in the sampling. Hence, seed sampling is one of the important activities of the shop floor or processing unit.

The management of storage in open and closed storage is critical before start of any seed processing activities. When seed lots reach the shop floor, they need to be stored properly. Unlike commercial produce seed lots cannot be stored in bulk. These need to be stacked lot wise and there is problem of “stackburn”-resulting from successive layers in building a bag stack. In crops like soyabean-”stackburn” can have detrimental effect on seed quality. The quality parameters like germination and viability can get lost instantly if not properly stacked on the pallets.

Storage of paddy seed lots after harvesting is one of the crucial aspects of processing shopfloor. Paddy due to increased mechanised harvesting may loose vital seed quality parameters. Since seed growers cannot buy a combined harvester themselves-they resort to hiring of this machine. Sometimes in the hurry of completing harvesting they harvest the crop at un-safe moisture content. This un-safe moisture content may go up to 50-60% also. Harvesting of seed crop with high moisture has adverse effect on storability. Ensuring safe seed moisture is very critical especially during rabi-summer seed production cycle. Most of the growers depend on sun drying for reducing the seed moisture. But paddy should not be dried >3% in one cycle. Follow tempering and convection cooling after every cycle and repeat the cycle till seed attains safe moisture content (14%).

Term ‘Scientific research’ is too broad to be explained by using one or two definitions. One should go through the different expert views about scientific research in order to internalize the concept of scientific research. In essence a scientific research is characterized by its rigor, testability, replicability, precision, confidence, objectivity, generalizability and parsimony.

Research: Uma Sekaran (2006) defined research as an organized, systematic, data-based, critical, objective, scientific inquiry or investigation into a specific problem, undertaken with the purpose of finding answers or solutions to it.

Rationally selected and contextually defined research problem is the foundation to the successful research project. If the selected research problem is not in line with the interests of the researcher, available time, resources, infrastructure & knowledge base then achieving success in research process remains highly uncertain. Consequently, in addition to hindering of professional growth of the researcher, it also results in wastage of time, money and human effort. Most importantly, it may sometimes add up incorrect knowledge into scientific base, hindering the process of scientific progress. Hence the identification of the research problem and designing the problem statement is the most important step in the research process.

Whenever we design a scientific study it is designed in a specific contextual background to solve one or another scientific problem. Subsequently it also involves a set of variables/phenomenon operating in a particular context, set of relationships among these variables and the conditions under which they operate. Certainly, to address an unsolved scientific problem we need to carry out research by employing well defined research methodology and have an idea about possible outcomes.  For example when a extension scientist is asked to study the impact of a novel programme, he needs to understand the background and the context under which the programme was introduced, what are the developmental inputs given under the programme, to whom, when (variables), with what purpose (context), what kind of impact he/she is supposed to investigate (presumed relationship), what methods he is going to use to investigate the impact of developmental programme (research methodology) and what are the possible outcomes of the investigation and how programme interventions are related to the outcome (relationship).

Most of the scientific research studies –except few descriptive survey research studies–will have one or more hypotheses to be tested as a part of study. Hypothesis is a prediction intended to be tested in a research study (Aron, Coups, and Aron, 2012). Hypothesis is the guide which directs the purpose and process of research by indicating the dependent and independent variables to be observed, extraneous variables to be controlled and the active variables to be manipulated.

Variable is any character or attribute of the given object/set of objects which varies from object to object or from one point of time to another point of time. For example height of individuals is a variable; it varies from person to person.  Kerlinger (1973) defined variable as a symbol to which numerals or values are assigned.

Importance of variables: In previous sections, we discussed about formulating the research problem and development of research hypothesis. Variables are the building blocks of any scientific research problem and research hypothesis. When we consider a hypothesis to be relational hypothesis, we mean that it make claims about relationship between two or more variables. When we test hypothesis, as such we do not test the hypothesis, rather we test the significance of hypothesised relationship between two or more variables. Since variables play central role in observation, measurement and testing of relationship, it is of prime importance to understand the meaning of variables, different types and the way we define these variables.

There can be no scientific studies which do not involve the process of measuring. Measurement process is the integral part of research activity. Measurement can be defined as the assignment of numerals to the objects or events according to set of rules.  The emphasis in this definition is on phrase ‘set of rules’. If the rules can be set up based on some rational or empirical basis, then theoretically anything can be measured. It is very much easy to understand the concept of measurement in case of physical sciences (Example weight, length, mass etc.) but it is harder understand the concept of measurement in case of psychological objects/phenomenon (intelligence, aggressiveness, attitude etc.) without understanding the predetermined rules of measurement. A rule is a guide, command that tells you what to do/how to do.

Reliability deals with the dependency, consistency, stability, predictability and accuracy of the research data. In our day to day life, when we say that a person is reliable then it means his behaviour is predictable, his behaviour (the way he behaved in past, he is behaving now and the way he will behave in future) will be consistent and he is dependable. On other hand an unreliable person’s behaviour is unpredictably variable and he cannot be depended upon.

In previous section, we discussed about the concept of the reliability and its importance. In this section, we will discuss about different types of reliability and procedures for estimation of the reliability. We already discussed that one cannot measure the reliability but of course it can be estimated.

Reliability aims at assessing the accuracy and consistency of whatsoever the measuring instrument measures irrespective of whether we are measuring what we are supposed to measure or not. Whereas the validity emphasises on the question “are we measuring what we were supposed to measure?”

To clarify the difference between reliability and validity, let us take an example of instruments that measure colour intensity. Assume, an expert develops two separate instruments X and Y to measure the intensity of green and red colour, respectively. But, the commercial manufacturer wrongly tags the red colour measuring instrument as X. When someone uses this wrongly tagged instrument for measuring the green colour intensity, whatever intensity values the instrument yields are reliable but not valid. It is so because the instrument is measuring red colour intensity accurately (hence data is reliable) but it is not measuring what it was supposed to measure –the green colour intensity (hence data is not valid).

In previous sections we discussed about the validity and estimation of validity. Now the question is whether the reliable and valid measuring instrument is sufficient condition to ensure the reliable and valid results in actual experiments? What if the measuring instruments are perfectly reliable and valid but the experiment is conducted in less controlled conditions? Can we expect accurate predictions under such conditions? The answer is No.

In previous section we discussed about the ability of the research design to precisely detect the relationship between cause and effect under controlled conditions. But in social research it becomes difficult to conduct the research under highly controlled conditions and moreover many of the researches in social science aim at prediction rather than understanding.

As we discussed earlier, aim of science is development theory, understanding, prediction and explanation of natural phenomenon. In many of the cases we are more interested in predicting the occurrence of social phenomenon rather than explaining it or understanding its relationship with other phenomenon. Under such conditions internal validity is of less use because a relationship that is established in artificially controlled conditions (with high internal validity) may fail to express itself in natural setup due to effect of extraneous variables. When the relationship between cause and effect is weak enough to be expressed in natural setup then it is of less use in predicting the phenomenon. Under such conditions we require experiments that are conducted in nearly natural setup, so that we can generalize the findings of the research to the wider domain.

Sampling is the process of drawing a part of population supposed to be the representative of that population.

Types: Sampling process can be either random or non-random. Most frequently we use random sampling method in our studies. But sometimes the purpose of the study demands for non-random sampling in one or other phase of sampling (Example: When we want to study the impact of life skills development programme on the disabled female beneficiaries)

Not all the scientific problems demand the detection and establishment of causal relationship among natural phenomenon. Many of the social research problems seek to study the status quo rather than the relation between two or more natural phenomenon. Few of the impact assessment studies (which are kind of causal relationship studies to an extent) also demand for knowing the status quo before and after implementation of interventions. Many other studies demand for benchmark assessment to make policy decisions. Under such circumstances, survey research is a useful research method.