Effects of Different Fertilizations on Fruit Quality, Yield and Soil Fertility in Field-Grown Kiwifruit Orchard
Kiwifruit yield and quality and soil nutrients were investigated in a kiwifruit orchard after long-term fertilization to understand the relationship between kiwifruit growth and soil nutrition. Seven fertilization treatments with three replications were applied in a continuous four-year period, including no fertilizer (CK); phosphorus (P) and potassium (K) fertilizers (PK); N and K fertilizers (NK); N and P fertilizers (NP); N, P and K fertilizers (NPK); 1.5 times of N, P and K fertilizers (1.5NPK); and chemical fertilizers plus swine manure (NPKM). Fertilization increased kiwifruit yield at the rate of 450 kg N/hm2, 225 kg P2O5/hm2, 300 kg K2O/hm2. The average yield decreased in a descending order for NPKM (44.6 t/hm2), 1.5NPK (42.6 t/hm2), NPK (42.0 t/hm2), NK (38.0 t/hm2), NP (36.7 t/hm2), PK (36.4 t/hm2) and CK (34.1 t/hm2). The sugar to acid ratio (S:A) was the highest (10.9) in 2012, and the soluble sugar increased by 15.7% after four-year NPKM fertilization. The NPKM fertilization also significantly increased the vitamin C, soluble solid and firmness. The soil organic carbon contents at 0-20 cm, 20-40 cm and 40-60 cm in depth under the NPKM treatment were 27%, 29% and 139% higher than that of the CK treatment, respectively. The available N contents at 0-20 cm, 20-40 cm and 40-60 cm in depth in the 1.5NPK treatment were 180%, 114% and 133% higher than that in the CK treatment, respectively. Balanced fertilization with N, P, K and organic manure is important to soil fertility, which may increase yield and improve quality in field-grown kiwifruit orchard.
Keywords: different fertilizations, kiwifruit yield, quality, soil fertility