Fertigation of Field Vegetable Crops

Response of field vegetable crop to S and Ca application is studied in on-farm field experiments conducted under fertigation conditions (with fertilizer application through drip irrigation).

IPNI-2015-RUS-4

29 Apr 2016

2015 Annual Interpretive Summary


Three on-farm experiments with field vegetable crops were conducted in 2015 in Gorodishche District, Volgograd Oblast. The light chestnut soil (Kastanozem; 0 to 30 cm depth) had a heavy texture, low salinity, medium organic matter content (2.2%), alkaline pH (7.4 to 8.2), medium available P, medium to high available K, and high available S. Calcium was a predominant exchangeable cation (74 to 76% of the cation exchange capacity). Depth to groundwater was from 8 to 11 m and it did not affect crop growth. Irrigation water had very low salinity and little suspended solids. A complex NPK fertilizer was applied in the fall that provided 120 kg/ha each of N, P2O5 and K2O.

The following fertigation treatments using ammonium nitrate (AN) and ammonium sulfate nitrate (ASN: 30% N, 7% S) were applied to onion (15 kg N/ha x 8 fertigations): 1) AN (typical farmer practice), 2) AN in 1 to 4 fertigations and ASN in 5 to 8 fertigations, and 3) ASN. There was no significant difference in marketable yield of onion bulbs between AN and ASN fertigation treatments in 2015 (76.8 t/ha vs 75.8 t/ha, respectively). A combination of AN and ASN gave a small (3 to 4%) but significant marketable yield increase compared to other treatments. Higher bulb weight was a reason for this yield improvement.

The following fertigation treatments with AN and ASN fertilizers were applied to bell pepper (15 kg N/ha x 8 fertigations): 1) AN (typical farmer practice), 2) AN + ASN (50% of N from each source), and 3) ASN. There was no significant difference in marketable yield of bell pepper fruits between AN and ASN fertigation treatments (53.9 t/ha vs 52.7 t/ha, respectively). However, a mixture of AN and ASN gave a noticeable (8 to 11%) but insignificant marketable yield increase compared to other treatments.

The following fertigation treatments with AN, ASN and calcium nitrate (CN) were applied to tomato (15 kg N/ha x 8 fertigations): 1) AN (typical farmer practice), 2) AN + CN (50% of N from each source), and 3) CN. Fertigation with CN resulted in the highest marketable yield of tomato (89 t/ha) compared to other treatments (75.4 t/ha with AN and 81.5 t/ha with AN+ASN). Both an increase in fruit number per plant and fruit weight contributed to such a considerable yield improvement. This means also a much better water use efficiency by tomato plants with CN application.