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Interpretive Summaries:
2005 - Effect of Balanced Fertilization for Fish Grasses in Hubei
2004 - Effect of Balance Fertilization on Fish Grasses in Hubei
2003 - Effect of Balanced Fertilization on Fish Grasses in Hubei
Effect of Balanced Fertilization on Fish Grasses in Hubei, 2003
Recent readjustments to the agricultural structure and better economic benefits from fish production are creating a new optimism for local economies in the Jianghan Plain. Five years ago, there were 7,000 hectares (ha) of arable land and 1,500 ha of fish ponds on the Datonhu State Farm. Now it has 3,000 ha of arable land and 5,500 ha fish ponds, and fish grass is very important in this production system. Every 15 to 20 kg fresh grass produces 1 kg of fish. An estimated 130,000 ha is planted to these grasses in the Jianghan Plain. Still, a large gap exists between supply and demand, so yield improvements will have a direct effect on total fish production. Grass production is still new to farmers and they lack knowledge concerning crop fertilization. Farmers generally depend on nitrogen (N) fertilization alone, but it contributes to low yields and efficiencies for both lands and fisheries. Field trials are underway to evaluate responses to N, phosphorus (P), and potassium (K) applications [applied as urea, single superphosphate (SSP), and potassium chloride (KCl)] on the main fish grasses.
Sorghum Sudanense: Four treatments (N, NP, NK, NPK) supplied nutrients at 540 kg N/ha, 150 kg P2O5/ha, and 135 kg K2O/ha. The NPK combination produced the highest yield (89.9 t/ha) from five harvests. Compared to Check (N only), yield increments for NP, NK and NPK fertilization were 11.1 t/ha (17%), 13.5 t/ha (20%), 23.4 t/ha (35%), respectively. Every harvest had a good response to P and K application, but the third harvest produced the highest response as NP increased yield by 28%, NK by 25%, and NPK by 49%. Results also clearly indicate that K fertilization extends the effective grass production season. Economic analysis determined that net profits due to PK application were up to US$472/ha greater than the Check.
Ryegrass: Six treatments [no fertilization (CK1), farmers’ practice (CK2), N, NP, NK, and NPK] supplied 114 kg N/ha (CK2), and combinations of 180 kg N/ha, 135 kg P2O5/ha, 180 kg K2O/ha for the remaining nutrient supplying treatments. From the first harvest on, grass height in all fertilization treatments was higher than that produced with no fertilizer. Grass height with NPK was 20, 9.1, 10.5, 6.8, and 11.0 cm higher than the CK1, CK2, N, NP, and NK treatments, respectively. NPK fertilization significantly increased seedling number by 34% compared to CK1. NPK produced 203% more grass yield compared to CK1, 157% more than NP, and 110% more that NK. Yield produced with CK2 was only 41% of that produced with NPK. Ryegrass responded well to N application alone as compared with CK1. More yield was obtained with 114 kg N/ha (+5.1 t/ha) and 180 kg N/ha (+14.0 t/ha). Ryegrass at this site was more responsive to P than K. Large economic benefits to all fertilization treatments resulted. However, profits from CK2 and the higher N only treatments were much lower than that obtained with more balanced treatments. Net profit with NP and NPK application was US$332/ha and US$413/ha, respectively.
Hybrid Millet: Twelve treatments provided various combinations of applied N, P, and K. Compared to a treatment supplying 90 kg P2O5/ha and 120 kg K2O/ha, fresh yield increased by 10.6, 18.3, and 22.0 t/ha, and profit increased by US$129, US$217, and US$246/ha with further addition of 60, 120, and 180 kg N/ha, respectively. Phosphorus application significantly promoted growth, yield, and profitability and the best result was produced with 90 kg P2O5/ha. Potassium improved yield only if applied in conjunction with N and P. Hubei-22
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