Nutrient Management on Potato

Potato is a staple food for mountain dwellers particularly in Chongqing, accounting for one-fourth of total foodstuff consumed annually. In those remote regions, potato yield and quality are usually low mainly due to shortage of good variety, nutrient management, and other related agronomic practices. Thus, how to improve potato yield and quality through balanced fertilization is of great importance for both better income and human nutrition. For this purpose, two field experiments were conducted on two soils, an acid, yellow earth soil with N and K deficiencies located in Wushan County, and another strongly acid soil (pH 4.1) developed from limestone with N, K, and Ca deficiencies located in Fengdu county. The experiments consisted of 11 treatments with three rates of N (75, 150, and 225 kg/ha at Wushan site; 90, 180, and 270 kg/ha at Fengdu site), four rates of P (0, 37.5, 75, and 112.5 kg P₂O₅/ha at Wushan site; 0, 45, 90, and 135 kg P₂O₅/ha at Fengdu site ), and four rates of K (0, 75, 150, and 225 kg K₂O/ha at both sites) and replicated three times. Lime was amended to the strongly acid soil at 1,500 kg/ha. The optimal treatment (OPT) was set at 150-75-150 kg N-P₂O₅-K₂O/ha at Wushan site and at 180-90-150-100 kg N-P₂O₅-K₂O-lime/ha at Fengdu site as identified by soil testing.

Results showed that potato yields at both sites significantly increased with an increase in N, P, or K rates and reached the highest yield (39.2 t/ha at Wushan and 27.2 t/ha at Fengdu) with the OPT treatment. The OPT produced 2.5 t/ha (6.4%) or 12.2 t/ha (31.2%) of commercial potato tubers more than the omitting P or K treatment at Wushan site, and 5.9 t/ha (22.8%) or 3.4 t/ha (13.3%) more than the omitting P or K treatment at Fengdu site, respectively. Omission of lime from the OPT significantly reduced potato yield by 10.7 t/ha (41.7%), the highest yield reduction in the experiment. It further demonstrated that contents of amino acids, proteins, and starch in potato tuber were generally increased quadratically with an increase in N, P, and K rates. However, vitamin C tended to decrease with increased N rates, while showing a positive response to P rates and not being influenced by K rates. Chongqing-BFDP-11-02