Approaching theoretical limits of productivity  of a crop in a given situation requires knowledge about  theoretical maximum productivity possible  for the phyto-climatic  potential of  the region, a function of  ideal climatic conditions with unlimited supply of nutrients. However ideal conditions  never exist; climatic variations and soil heterogeneity imposes a correction factor  and the productivity varies widely from zone to zone. Agro climatic  potential  takes into account variations in temperature, rain and irrigation water use efficiency  and, sunshine hours through the growing season  to arrive at productivity that could be achieved when other management factors are not limiting it. (Ranganathan, 2014). In any situation, there are two facets of limiting forces to look into before deciding the target. (1) The maximum productivity achievable with the climate – temperature, sunshine hours and rainfall and its distribution is called climate limiting threshold productivity under rain fed conditions. Of these, only water availability is manageable and it is known as the threshold limit with irrigation potential of the area.  (2)  The threshold productivity from nutrients available through natural recycling process with or without recycling the organic residues at harvest. Only the economic end product for which the crop is grown, should be taken away from the field. The threshold productivity depends on soil’s  physical, chemical and physicochemical properties of soil, particularly soil structure stabilized by humus compounds which play important role in water storage, retention  and release of nutrients for the growth of plants. This part is looked after by recycling of all crop residues other than the economic end product, addition of organic matter and  raising green crops and plough them in situ before planting or as inter crops in  tree gardens.  These are  referred as soil factors limiting thresh hold  potential.  (3) The target is fixed  between the above two limits depending on nutrients availability and   other factors  like labor availability, logistic factors for handling higher volume of  the  product and demands  in the market. Discussions are restricted only to the role of water and   nutrients to achieve a set target in productivity in this paper  Keywords: Threshold, Maximum and  limits of productivity