The statement 1 is incorrect. Quite the contrary, a high content of organic matter in soil increases its water holding capacity as organic matter can absorb water like a sponge, storing it for later use by plants. Organic matter improves the soil`s structure, porosity, and density, which all contribute to greater water-holding capacity.

The statement 2 is also incorrect. Soil plays a significant role in the sulfur cycle. Plants obtain sulfur from the soil and convert it into organic substances. When plants and animals die, the sulfur becomes part of the soil again.

The statement 3 is correct. Ongoing irrigation can indeed contribute to the salinization of some agricultural lands. This generally happens when the water used for irrigation contains salts, which accumulate in the soil over time. This can lead to a decline in soil fertility and a decrease in agricultural productivity.

Therefore, the correct answer is option 2, which states that only the 3rd statement is correct.