A Vaastu compliant land or plot radiates positive energy while a non-Vaastu complaint land can generate negative energy if there is a problem with the direction, light, wind, materials used in construction and the type of structure being built. There are five important aspects in selecting a land such as soil, location, topography, direction and shape. Primarily in buying a land one needs to have closer look at the quality of land itself. Viz.,
Sandy, rocky, sticky/muddy or mix of these is found around the world in various terrains. For instance, Rajasthan and Gujarat have more sandy varieties whereas southern parts of India have either black or rocky or alluvial soils. Further north in Himalayan range land can be sharply sloping as in the valley or mountain.
Of course, there has to be a point of convergence between different forms of land but the basic unit remains and it is the square. Square is congruent with the human body and many other shapes, including the circle. The system of division based upon units of square can be traced to Vedic times and will remain same for time to come.
Nothing can match for residential purpose than land in rectangular or square shape. Heptagon, hexagon, and triangle are not advisable as they generate negative energies and take a toll of mental well-being. If no choice exists one may take them as remedies are available to allay the negative energies emanating from these odd shaped plots.
Another aspect is undue emphasis is given on gravitational energy of the earth as per the location of the land. These are rumours and spread by those who are prone to question Vaastu as being different from place to place and even in poles with North and South poles having different Vaastu application. They also say that Vaastu differs state-wise and population-wise.
I don’t subscribe to these theories as our concept of Vaastu in modern times has been clearly delineated from those that may be quoted from Mayamatam, Manasara or other classical books on Vaastu Shastra.