Crop Production Management - Free MCQ Practice Test with solutions,

River lift system is where water from rivers is drawn directly to supplement irrigation schemes. River lift systems do not depend on the natural flow of water from rivers by gravity through canals, rather it employs other means such as pumps and direct fetching. This system is used in regions where the water flow from the canals or reservoirs is insufficient to supply the farms. 

Parthenium hysterophorus is a noxious weed in America, Asia, Africa and Australia. This weed is known to cause many health hazards which have now reached epidemic proportions. This weed is considered to be a cause of allergic respiratory problems, contact dermatitis, mutagenicity in human and livestock. Crop production is drastically reduced owing to its allelopathy. Also aggressive dominance of this weed threatens biodiversity. 

The practice of cultivating two or more crops simultaneously on the same piece of land is called mixed cropping. During mixed cropping, if one crop faces adverse conditions or pathogen attack then the other crop can be saved. Wheat and maize cannot be grown together as wheat is a rabi crop and maize is a kharif crop.

In relatively large amounts, the soil supplies nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur; these are often called the macronutrients. Micronutrients are required by plants in far smaller quantities than any macronutrient. Micronutrients required by plants include zinc (Zn), iron (Fe), manganese (Mn), copper (Cu), boron (B), molybdenum (Mo), and chlorine (Cl). Relative to the macronutrients, micronutrients are required in trace quantities.

Soil supplies 13 essential nutrients for plant growth. These nutrients are divided into two categories:

Macronutrients:

1. Nitrogen (N)
2. Phosphorus (P)
3. Potassium (K)
4. Calcium (Ca)
5. Magnesium (Mg)
6. Sulfur (S)

Micronutrients:

1. Iron (Fe)
2. Manganese (Mn)
3. Boron (B)
4. Molybdenum (Mo)
5. Copper (Cu)
6. Zinc (Zn)
7. Chlorine (Cl)

These nutrients are crucial for various physiological functions and healthy plant development.

In simplest terms, agriculture needs water, and in India much of this water traditionally comes from the monsoon. Crop failure happens more in catastrophic weather conditions in which the crops are wiped out by floods or droughts. 

Sulphur is an essential nutrient for plant growth. Most of the sulphur in soils is found soil in organic matter . However, it is not available to plants in this form. In order to become available to plants, the sulphur must be first released from the organic matter and go through mineralization process.

All plants require nitrogen, phosphorus and potassium as their primary nutrient. Thus oxygen is not considered as primary nutrient for plants.