Mainly, it is the soil under the tree is sloughed off and there is no shaping to concentrate the nutrients. Please see below for more details.

According to the question, combined with the title of the following picture observation, I believe that your home planted citrus trees have been a few years have not grown big for two main reasons: one is the citrus tree under the weeds, soil crust, the root system is not developed; the other is the citrus tree is not shaping the tree, belonging to the natural growth type, the nutrients are not concentrated, affecting the photosynthesis.

●Citrus trees under the weeds, soil crust, undeveloped root system, lack of nutrients:

From the picture, we can see that the subject is the citrus trees planted in the ridge, one side of the side in the ground, the citrus tree's root system can only be to the ground in the soil growth, but can not be to the ridge side of the side of the ridge in the soil-free expansion of the soil, the root growth is greatly restricted, and therefore absorbed the water and nutrients are much less. The root growth is greatly restricted, thus absorbing much less water and nutrients. The weeds under the citrus trees (thatch grass) grow luxuriantly and also compete fiercely with the citrus trees for water and nutrients. Since the root system of thatch is both strong and deep, it seriously competes with the citrus trees for water and nutrients, and thus the trees lack the water and nutrients they need to grow. At the same time, only a small piece of soil under the citrus tree at the root and stem is loosened by your digging, and does not extend far away because the soil is compacted, which is not conducive to the root system to grow far away. Under normal circumstances, the length of the root system of a citrus tree is equal to the height of the tree, i.e., the roots are as long as the tree is tall. However, due to overgrown weeds under the tree and soil compaction, the root growth of citrus trees is restricted, resulting in short roots and high trees, i.e., "root-crown disproportion", the tree is top-heavy, and thus citrus trees grow slowly.

●The citrus tree has not been shaped, belongs to the natural growth type, the nutrients are not concentrated, affecting photosynthesis:

From the picture, we can see that the citrus tree planted by the questioner has not been shaped, belongs to the natural growth type, not only is the nutrients dispersed, but also affects photosynthesis by the crowded and overlapping leaves.

The subject can prune now, and later combine with winter pruning and shaping. Shaping can use two main branches or three main branches natural happy type, that is, from the lower part of the citrus tree in different directions to leave two or three main trunk upward growth, and then in the main trunk to leave the deputy main branch, in the deputy main branch and then leave the twigs method. The overcrowded, weak, overlapping, no sunlight, dry, insect-infested branches are all cut out, so that the remaining branches can receive sunlight, so that the nutrients are concentrated, the citrus tree can grow big, more fruit, good fruit.

The subject's home planted citrus trees have been a few years have not grown the reason, mainly under the tree soil slump, overgrown weeds, is not conducive to the growth of the root system. There is also the lack of citrus tree shaping pruning, branch and leaf overlap, the growth of some useless branches and leaves, nutrients are ineffective consumption.

The solution is to remove the weeds under the tree (thatch grass), pick out the roots and dig the soil under the tree loose, dig far away from the edge of the inter-root application of composite fertilizer, and then apply three to four times of fertilizer to nitrogen fertilizer ( urea etc. ) is the main. At the same time, the citrus tree shaping pruning, to avoid nutrition is ineffective consumption.