Effect of different rates of potassium incorporated with chicken manure biochar on the growth, yield and eating quality of sweet corn (Zea mays L.)

This study study was carried out at the Faculty of Sustainable Agriculture, Universiti Malaysia Sabah (UMS) Sandakan Campus from June to September 2016 to evaluate the effect of potassium (90:60:40, 90:60:50, 90:60:60, 90:60:70, 90:60:80, and 90:60:90) incorporated with application of chicken manure biochar (20 t ha-1) on the growth, yield and eating quality of Improved Mas Madu sweet com planted on Silabukan soil. The nutrient content for Silabukan soil series was also investigated after the experiment. The treatments that involved in this study were control (NPK 90:60:60 kg ha-1 without chicken manure applications), chicken manure biochar treatment and six different rates of potassium fertilizer which were 40 kg ha-1, 50 kg ha-1, 60 kg ha-1, 70 kg ha-1, 80 kg ha-1 dan 90 kg ha-1 while the rate of application for chicken manure biochar were 20 t ha-1 incorporated with each treatment. These treatments were arranged as a one-way completely randomized design (CRD) with five replications. Data collected were analysed using one-way anova at 5% significant difference. The results showed that for vegetative growth of Improved Mas Madu sweet com crop, treatment T7 gave the tallest plant height and the most amount of leaf number's which were 260.24 cm and 11.2, respectively. Treatment TS showed the highest first cob height from soil surface which was 123.9 cm. For the yield component, treatment T2 gave the longest length of cob that was 17.08 cm whereas treatment TS gave the heaviest wet weight of cob which was 114.02 g. Treatment T7 gave the longest diameter of cob and cob girth which were 4.02 cm and 12.63 cm, respectively. Treatment T2 gave the most number of grains per cob which was 405 grains and treatment T3 gave the heaviest weight of 100 grains per cob which was 10.12 g. Furthermore, treatment T7 gave the highest extrapolated dried cobs yield which was 3.35 tonnes per hectare and treatment T3 gave the highest extrapolated grain yield which was 1.77 tonnes per hectare. For mean root dry weight, treatment T6 showed the heaviest mean root dry weight which was 36.9g. For the total soluble solids °content, treatment T4 gave the highest brix reading which was 19.13 brix. For Silabukan's soil chemical properties, treatment T7 had the highest pH value and total nitrogen content by which 6.16 and 2.18%, respectively, meanwhile treatment TS had the highest available phosphorus which was 1.846 ppm. This experiment revealed that treatment Tl (control) gave the shortest plant height, least mean number of leaves, shortest length of cob, lowest weight of cob, shortest diameter of cob, shortest cob girth, least number of grains, lowest weight of 100 grains, lowest extrapolated dried cob yield, lowest extrapolated grain yield and lowest total soluble solid content which were 76.2 cm, 9.8 mean leaves, 12.34 cm, 59.15 g, 2.79 cm, 8.76 cm, 201 grains, 4.74 g, 1.98 tonnes per hectare, 1.41 tonnes per hectare and 16.93°brix content, respectively. Meanwhile, treatment T2 gave the shortest first cob height from soil surface which was 85.04 cm. Thus, the best treatment that can be recommended to the farmers is treatment T7 (90:60:90 NPK kg ha-1 incorporated with 20 t ha-1 chicken manure biochar) because the treatment had highest extrapolated dried cobs yield, 3.35 tonnes per hectare and longest cob girth, 12.63 cm. Besides, the second best treatment that can be recommended was treatment TS (90:60:70 NPK kg ha-1 incorporated with 20 t ha-1 chicken manure biochar) because this treatment had the heaviest weight of cob, 114.02 g and the third highest for extrapolated dried cobs yield 2.66 tons ha-1