i would like to get details on disadvantages of automatic plant irrigation system

To get information about disadvantages of automatic plant irrigation system refer the links below



http://studentbank.in/report-disadvantag...controller

http://studentbank.in/report-automatic-p...-wikipedia

The post explains a simple yet effective automatic plant irrigation system circuit which can be used for automatically sensing soil humidity and triggering a water pump when the ground gets parched below a predetermined level (adjustable).


The circuit is rather straightforward and uses a single IC 555 as the main active component.

Referring to the automatic plant irrigation circuit shown below we can see the IC 555 is wired in a completely unique and in the quickest possible mode.
Here it's configured as a comparator, and works better than an opamp because the IC 555 has built in opamps which are at par with any single opamp and also the output of a 555 IC is able to sink sufficient current in order to drive a relay without a transistor driver stage.

The above features particularly makes the above design very simple, low cost and yet too effective with its functions.

The pin#2 here becomes the sensing pinout of the IC, and is held at ground level via R2 which must be calculated as per the desired soil humidity triggering threshold.

The points A and B can be seen fixed inside the soil which needs to be monitored for the intended automatic watering from the water pump.

As long as the points A and B senses some level of humidity corresponding to a resistance value which may be lower than R2, the IC 555 output is held low, which in turn keeps the relay deactivated.

However as the soil tends to get dryer, the resistance across the probes starts getting higher and at some moment of time it becomes higher than R2, creating a potential below 1/3rd supply voltage at pin#2 of IC555.

The above situation instantly prompts pin#3 of the IC to become high, triggering the connected relay.

The relay activation switches ON the water pump which now starts pumping water to the particular area of the soil via a distributing water channel.

As this happen, the soil gradually gets wetter and as soon as the predetermined level is reached, the probes immediately sense the lower resistance and revert the IC ouput pin#3 to a low again switching OFF the relay and the water pump consequently.



ADVANTAGES
1. Saves water - Studies show that drip irrigation systems use
30 - 50% less water than conventional watering methods, such
as sprinklers.
2. Improves growth - Smaller amounts of water applied over a
longer amount of time provide ideal growing conditions. Drip
irrigation extends watering times for plants, and prevents soil
erosion and nutrient runoff. Also, because the flow is continuous,
water penetrates deeply into the soil to get well down
into the root zone.
3. Discourages weeds - Water is only delivered where it's
needed.
4. Saves time - Setting and moving sprinklers is not required.
A timer delay as per environment can be added to the system
for automatic watering.
5. Helps control fungal diseases, which grow quickly under
moist conditions. Also, wet foliage can spread disease.
6. Adaptable - A drip irrigation system can be modified easily
to adjust to the changing needs of a garden or lawn.
7. Simplest Method - Start by drawing a map of your garden
and yard, showing the location of plantings. Measure the distances
required for lengths of hose or plastic tubing to reach
the desired areas.