Production and chemical quality of sweet corn with single fertilizer combination (SFC) on upland in West Papua

Sweet corn is popular in West Papua. This study was aimed at determining the production and chemical qualities of sweet corns using single fertilizer combination (SFC). A completely randomized design experiment was used with 5 treatments and 3 replications. The treatments were without fertilization (P0), with a concentration of P1 (22.4g/plant); P2 (23.52/plant); P3 (24.64g/plant); P4 (25.76g/plant). Variables observed were weight, length, diameter, pH, water, ash and fat content. The data obtained were analysed using analysis of variance continued with the Honest Significant Difference Test. Results showed that different concentrations gave a very significant difference (P<0.01) on cob weights (gr) (P0, P1, P2, P3, P4 were 51.39; 115.40; 133.06), cob lengths (mm) (78.45; 107.37; 113.92; 131.54;141.02), and cob diameters (mm) (24.56; 31.22; 34.29; 36.21; 37.55); did not give a significant difference (P>0.05) on pH (5.47; 5.37; 5.41; 5.40; 5.38), moisture content (%) (60.41; 60.75; 60.29; 60.08; 60.08), ash content (%) (1.95; 2.07; 2.05; 1.96; 1.92), and fat content (%) (0.62; 0.53; 0.43; 0.52; 0.40). The conclusion was that different concentrations of SFC did not give a different effect on pH, water, ash, fat content and gave a very significant difference effect on weight, length, diameter of sweet corn cobs.


Introduction
Sweet corn (Zea mays Saccharata) is one of the food crops promising with economic value and is popular with Indonesian people.According to Arsyad (2019), The nutritional value of sweet corn is slightly different from that of regular corn [1].The sweet taste of sweet corn occurs because the carbohydrates in corn kernels contain reducing sugars (glucose and fructose), sucrose, polysaccharides and starch.Sweet corn can be served as processed food or cooked conventionally such as boiled, steamed, grilled, smoked and grilled.Snack foods from sweet corn processed with these conventional ways are easily found, one of which is in West Papua.
West Papua province with the capital Manokwari is one of new provinces in Indonesia.Sustainable development of both infrastructure and human resources is the main target of the government.Along

Methodology
The tools used in this study include: portable upland soils test kit, 500ml measuring glass (Pyrex), 500ml erlenmeyer (Pyrex), precision balance (Kern -PLJ6200-2A), mixer, digital caliper (krisbow-tactix), meter tape, pH meter (Jenway 3510), sample box.Materials used include: sweet corn seeds, aquadest, single fertilizers (Urea, SP-36 and KCl).This research was conducted for 3 months starting from June -August 2022.It was carried out in the assessment installation and laboratory of West Papua Assessment Institute of Agricultural Technology with the observed variables: weight, cob length, cob diameter, pH, moisture content, ash content and fat content.The research was conducted with field and laboratory trials using a completely randomized design with 5 treatments and 3 replications.The treatments tried included P0 (without fertilization), single fertilizer combination P1 (22.4g/plant);P2 (23.52/plant);P3 (24.64g/plant) and P4 (25.76g/plant).The recommended dose of single fertilizers (P1) was obtained using a portable upland soil test kit.The ratio of single fertilizers (Urea : SP-36 : KCl) was 3.5 : 2.5 : 1. Fertilizers dose was divided in half and given to plants on the 15 th and 45 th day after planting.
Research variables were weight measurement (g) [7]: The weight measurement was carried out by weighing the cobs that had been peeled from the cornhusk using a scale.Cob length measurement (mm) [8]: Cob length measurement was done after harvest, after the cobs are separated from the husk or peeled off.Measurements were made from the base to the tip of the cob using a tape measure or the like.Cob diameter measurement (mm) [7]: Cob diameter was measured after harvest, after the cobs were separated from the husks.Measurements were made using a caliper.pH measurement [9]: The pH value of corn was measured using a digital laboratory benchtop pH meter.Samples were prepared by inserting 100grams of mashed corn kernels into a beaker glass then stirred until homogeneous.Prior to measurement, the pH meter was calibrated using a standard buffer solution of pH 4, 7 and 10.The pH measurement is carried out by immersing the electrode in the sample and the reading on the screen is recorded if it does not change significantly for more than 5 seconds.The electrode is rinsed with aquadest every time a measurement is taken.Moisture content measurement [10]: Heat a clean weighing bottle in an oven at 105°C for 1 hour and then cool in a desiccator for 20 minutes then weigh and record the weight (w0).Weigh 1 gram of sample (s) in a weighing bottle of known weight and then dry it in an oven at 105°C for 24 hours.Cool the weighing bottle with the sample in the desiccator for 20 minutes then weigh and record the weight.Put the weighing bottle with the sample back in the oven at 105°C for 1 hour and cool again in the desiccator for 20 minutes, then weigh and record the weight again.Repeat heating in the oven, cooling and weighing until a constant weight (w1) is obtained where the difference in successive weighing is less than 0.0002g.The water content is calculated as follows: Moisture content (%)=[(w0+s)-w1]/s ×100.Ash content measurement [10]: Heat crucibles in in a 550°C muffle furnace for 24 hours.Cool in a desiccator for 30 minutes then weigh and record the weight (w0).Weigh 3g sample (s) in the crucibles of previously known weight.Place the crucibles with samples in muffle furnace at 550°C for 24 hours.Turn off the muffle furnace and allow it to cool.Remove the crucibles from the muffle furnace and place into a desiccator to cool for 30 minutes then weigh and record the weight.Place the crucibles into an oven at 105°C for 1 hour then cool in a desiccator for 20 minutes then weigh and record the weight.Repeat heating in the oven, cooling and weighing until a constant weight (w1) is obtained where the difference in successive weighing is less than 0.0002g.The water content is calculated as follows: Ash content (%)=(w1-w0)/s ×100.Fat content measurement [10]: Heat Soxhlet beakers containing boiling stones in an oven at 105°C for 1 hour then cool in a desiccator for 20 minutes then weigh and record the weight (w0).Weigh 1 gram of sample (s) on filter paper then wrap it in filter paper and put it in a Soxhlet beaker.Put the solvent into the Soxhlet beaker containing the sample and run the extraction.Heat the beaker containing the extraction results in the oven at 105°C for 24 hours.Cool in a desiccator for 20 minutes then weigh and record the weight.Place it back into the oven at 105°C for 1 hour then cooled in a desiccator for 20 minutes then weighed and recorded the weight.Repeat heating in the oven, cooling and weighing until a constant weight (w1) is obtained where the difference in successive weighing is less than 0.0002g.The fat content is calculated as follows: Fat content (%)=(w0-w1)/s ×100.

Results
Effects of a single fertilizer combination on upland on weight, cob length, cob diameter, pH, moisture content, ash content and fat content of sweet corn is shown in Table 1 and Table 2. Based on the data in Table 1, it is known that the single fertilizer combination treatment at different levels gave a very significant difference (P<0.01) on weight, cob length and cob diameter of sweet corn.Based on the data in Table 2, it is known that the single fertilizer combination treatment at different levels did not give a significant difference in effect (P>0.05) on pH, moisture content, ash content and fat content of sweet corn.The treatment followed by the same symbol is not significantly different and vice versa.

Weight of sweet corn
Based on the results of the analysis of variance (Table 1) it is known that the treatment of giving a single fertilizer combination to sweet corn planted on upland resulted in a very significant difference (P <0.01) on the weight of sweet corn.The P4 treatment produced the highest sweet corn weight value of 199.13g.
Increasing the concentration level of the combination of urea fertilizer: SP36: KCl can increase the production of sweet corn.The combination of single fertilizer was able to increase the weight of sweet corn when compared to P0 (control), P1, P2 and P3.The weight of sweet corn for each treatment respectively was P0 51.26g<P1 115.15g<P2 133.07g<P3 177.89g<P4 199.13g.In a research conducted by Shaila (2019), the combination treatment of fertilizer with the highest dose (h3), namely, 200 kg/ha urea and 15 ml/liter of liquid organic fertilizer produced a significant difference in effect on plant height, leaf area, cob diameter, cob length, cob weight per plant, and cob yield per plot.The average weight of sweet corn increased with increasing fertilization doses [11].
Single fertilizer contains nutrients that affect the differences in the effect of the treatments tried.The single fertilizer combination given contains the nutrients N and P. Both are known to be very important in the process of growth (cob formation) and development (seed filling).These nutrients are in free in plant tissue so that when needed they must be distributed immediately to the parts of the plant that need them.This role can be especially observed in young plants which are still in a period of rapid growth and development.Wirayuda (2020) stated that in carrying out metabolic processes, plants need nutrients [12].The vegetative period is a critical point for plant growth.Nutrients are used to encourage division and the formation of new cells in order to form plant organs such as leaves and stems that are better so as to facilitate the process of photosynthesis.The different single fertilizer combination treatments showed a very significant difference in the weight of sweet corn.Weight is a production indicator that is often observed.Weight is the mass of an object in the form of a scale obtained from measurement results due to the gravitational force of an object [13].The higher the value read from the measurement results, the higher the weight of the object.High weight can be associated with high production.Proper application of fertilizer during the growth of corn plants can increase corn yields [14].
In Table 1, it can be seen that the average weight of sweet corn increased with increasing concentration of a single fertilizer combination.Fertilizers can provide the nutrients plants need to grow and develop.The nutrients contained in each single fertilizer used include: urea containing 46.04% N, SP36 containing 36% phosphate and 5% sulfur and KCl containing 60% K2O [15; 16; 17].[18], stated that the use of inorganic fertilizers on sweet corn plants is generally done because it can supply the three nutrients such as nitrogen, phosphorus and potassium in certain ratios.Urea fertilizer is a fertilizer with a high N content which is beneficial for plants for vegetative growth and development of plants such as roots, stems and leaves.Urea is a fertilizer with a high N content which is beneficial for plants for vegetative growth and development of plants such as roots, stems and leaves.The maximum growth of plant parts will support plant production [19].Phosphate contained in SP36 is useful in improving soil nutrient structure, early root growth, flower and seed growth and increasing plant resistance to pests and diseases [20].Meanwhile, KCl has important benefits in the formation of carbohydrates and proteins during plant production, especially seed enlargement/filling [21].
Adequate nutrients by giving a single fertilizer combination can increase production.The combination of a single fertilizer given is thought to be able to improve the nutrient structure of the upland used.Fertilization that is done both with inorganic and organic fertilizers can meet the nutritional needs needed by plants.From the sweet corn production data in Table 1, it can be seen that there is a very significant difference in effect between the treatment with a single fertilizer combination compared to no fertilizer application.Treatment without a single fertilizer combination resulted in the lowest weight value of sweet corn indicating that production was not optimal.While the weight of sweet corn in the treatment of the combination of single fertilizers increased with increasing concentration of the dose of the single fertilizer combination given.The best treatment can be seen at P4 which produces the highest weight value of sweet corn.The results of research by Puspadewi, Sutari and Kusumiyati (2016) showed that the combination of biological fertilizers and NPK fertilizer for sweet corn of the Talenta variety affected plant height, stem diameter, leaf area, cob length, cob diameter, cob weight, plant yield, harvest index and total soluble solids of sweet corn.Cob weight value in the treatment increased with increasing concentration of the combination of biological fertilizers with NPK given: 1 POC + 1 NPK of 280.56g and 2 POC + 1 NPK of 281.63g [22].In line with Mutaqin, Saputra, and Ahyuni (2021) stated that the higher the concentration of the KCl fertilizer dose given, the higher the weight of sweet corn.The production yield value of sweet corn weight for each treatment was 0 kg/ha 365.6 g; 50 kg/ ha 425.6g; 100 kg/ ha 417.5 g and 150 kg/ ha 460.4 g [23].

Length of sweet corn cobs
Based on the results of the analysis of variance (Table 1), it was found that the treatment of the application of a single fertilizer combination to sweet corn grown on upland produced a very significant difference (P <0.01) on the length of sweet corn cobs.The P4 treatment produced the highest cob length value of sweet corn 141.02mm.The combination of single fertilizer was able to increase the length of sweet corn cobs when compared to P0 (control), P1, P2 and P3.The length of sweet corn cobs for each treatment, respectively was P0 78.45mm< P1 107.37mm<P2 113.92mm<P3 131.54mm<P4 141.02mm Cob length is one of the components of sweet corn production.In Table 1, it can be seen that the application of a single fertilizer combination treatment gave a very significant difference in the effect on the length of the sweet corn cobs.Length is the observed value of the parameter scale of the ruler used.The greater the value of the measurement results obtained, the longer the length of the sweet corn cobs.Single fertilizer combination treatment (P1, P2, P3 and P4) has higher cob length values than no fertilizer treatment (P0).The higher the dose concentration of the single fertilizer combination from P1<P2<P3<P4 the higher the cob length value.The highest corn cob length value was found in the P4 treatment with the highest concentration of a single fertilizer combination dose of 25,76g/plant.Hayati (2012) stated that the application of fertilizers had a significant difference in effect on the weight and length of the cobs of sweet corn [20].The mean cob length in the treatment with the combination of urea and chicken manure was higher than the control treatment.The higher the dose concentration of the combination of urea fertilizer and chicken manure, the higher the cob length value produced.The treatment of giving a combination of urea fertilizer with chicken manure was able to increase the length of sweet corn cobs by 25 P4 is the best treatment because it produces maximum production in the form of the highest cob length by utilizing nutrients from optimal fertilization treatment.Fertilizer treatment will provide nutrients for plants to grow and produce.Cob length can be associated with production because the longer the corn cob, the more corn kernels produced.Corn kernels generally grow and fill along the corncob area, so the length of the cob is also related to the weight of the corn.The longer the corn cob, the heavier the corn will be.Puspadewi (2016), stated that the number of seeds formed on sweet corn cobs was positively correlated with the increased length of sweet corn cobs [22].The longer the corn cob, the more potential the seeds will form.This production process cannot be separated from the growth and development of sweet corn plants.The availability of sufficient nutrients when plants grow and develop determines the physiological potential of plants.These nutrients will be consumed by plant cells and form each part of the plant optimally.The growth of the plant can be observed from both increases in size (length) and volume (diameter).
Orebo (2021) stated that the combined treatment of nitrogen, phosphorus, sulfur and boron fertilizers (NPSB) produced a significant difference in the effect on cob length of three varieties of corn namely, 30G19, BH-546 and BH-547 [8].The highest average cob length value of 20.79cm was obtained from the NPSB treatment of 100 kg/ha).The higher average cob length value of the NPSB fertilizer combination treatment compared to the control is thought to be because the fertilizer provides nutrients for plants during the growth and development period.During the process of growth and development there is an increase in cell elongation and vegetative growth which is the physiological stage of the plant.This is inversely proportional to plants that are not given fertilizer treatment.Petroganic fertilizers provide the nutrients needed and can be absorbed by plants.Nutrients from these fertilizers are used to carry out metabolic processes, especially during the vegetative period which are used to encourage cell division and the formation of new cells to form better plant organs such as leaves and stems [24].

Diameter of sweet corn cobs
Based on the results of the analysis of variance (Table 1) it is known that the treatment of the application of single fertilizers combination to sweet corn planted on upland resulted in a very significant difference (P <0.01) on the diameter of the sweet corn cobs.The P4 treatment resulted in the highest sweet corn cob diameter value of 37.55mm.The combination of single fertilizer can increase the diameter of sweet corn cobs when compared to P0 (control).The diameter of the sweet corn cob for each treatment was P0 24.56mm<P1 31.22mm<P234.29mm<P3 36.21mm<P437.55mm.
Cob diameter can be associated as a volume obtained from the measurement results using a caliper.The higher the average value obtained, the higher the value of sweet corn production.Larger diameter has a positive correlation with the size and weight of sweet corn cobs.Large size and weight can be obtained from the seed filling process during the growth and development of sweet corn.Puspadewi (2016) stated that during the generative phase there was a process of filling sweet corn seeds and increasing the diameter of the sweet corn cob [22].The development and increase in size due to seed filling represents the results of the growth and development stages of the corncob which generally increase in terms of size (length) and volume (diameter).The process of filling the corn kernels is the role of the available nutrients due to the combination of fertilizer treatments given.Nutrients from the fertilizer that were given were then absorbed by the plants during growth.Nutrients absorbed will be processed during photosynthesis to produce carbohydrates and proteins.Carbohydrates and proteins that are formed will be accumulated in the leaves which can be used in forming/filling corn kernels.According to Taufik (2022),the formation of proteins, carbohydrates and starches takes place well in plants due to the fulfillment of nutrient needs [25].Nutrients from these fertilizers are utilized by plants in metabolic processes so that they run optimally.The results of these metabolic processes accumulate in the formation of seeds so that the seeds formed have maximum size and weight.
In Table 1, it can be seen that the three components of sweet corn production increased with increasing concentration of the dose of the fertilizer combination given.There is a positive correlation of the three parameters of sweet corn production.The higher the weight and length of the cob, the higher the average diameter of the sweet corn cob.Nutrients can increase the length of the cob and the diameter of the corn cob.Alfian (2019) stated that the length and diameter of the cob shows the shape of the cob itself which can affect the weight of the cob [21].The longer and wider the cob diameter, the more seeds contained in the cob so that the cob weight is greater.The maximum production parameters can be achieved because sweet corn plants are able to optimally utilize the fertilizer given.Plants need fertilizer nutrients given during the growth stage.The need for nutrients that are met, enough sunlight and water during the photosynthesis process make the plant's metabolism run optimally.The optimal cell metabolism produces various substances such as carbohydrates, proteins and fats.The photosynthate produced will be transferred and stored in the seeds when filling the seeds [26].

pH of sweet corn
Based on the results of the analysis of variance (Table 2) it is known that the treatment of giving a single fertilizers combination to sweet corn planted on upland did not produce a significant difference in effect (P> 0.05) on sweet corn pH.The combination of a single fertilizer is thought to have the same effect on the pH of sweet corn in each treatment P0 (control), P1, P2, P3 and P4.The pH of sweet corn for each treatment was P0 5.47; P1 5.37; P2 5.41; P3 5.40 and P4 5.38.The pH value is a parameter that indicates the acidity level of a food ingredient.In general, corn has a pH value that is neutral or close to neutral.Generally, sweet corn pH ranges between 5.90-7.50[27].The average pH value of this study was lower than other studies, allegedly due toeffects of respiration that has occurred in sweet corn that has been stored for more than 7 days at fluctuating room temperature.One of products of cellular respiration is carbondioxide (CO 2 ).Carbon dioxide can dissolve into water forming carbonic acid (H 2 CO 3 ).Carbonic acid is a weak organic acid which has a slightly acidic pH of 5.7 in normal atmospherics conditions.Therefore, the more CO 2 is produced, the more likely it is for the formation of carbonic acid to drive down the pH Ding (2021) reported that the pH level of sweet corn was observed during treatments [28].The treatment of storage time, storage temperature and cooling time on sweet corn has been observed.The results showed that storage time and storage temperature showed a significant difference in the pH value of sweet corn.While the cooling time treatment did not show a significant difference in effect.The longer the storage time, the lower the pH value.Long storage treatments of 0, 2, 4, 6 and 8 days resulted in a pH value of 7.03; 8.98; 6.99; 6.90 and 6.69.The higher the storage temperature, the lower the pH value.Storage temperature treatments of 12 and 25 o C resulted in pH values of 6.95 and 6.89 respectively.While the cooling time treatment of 0, ½ and 7/8 resulted in a stable pH value and did not change too much.Treatment of cooling time 0, ½ and 7/8 cooling time (CT) resulted in a pH value of 6.91; 6.92 and 6.93.The decrease in the pH value is thought to be due to the respiration process by the sweet corn during storage.The longer the storage time, the longer it will take so that the corn undergoes respiration for a long time.Likewise, at the storage temperature, the higher the temperature used, the faster the respiration process occurs.The respiration process that occurs in both treatments might change the chemical composition in the cellular environment which is thought to have contributed to the decrease in the pH value of sweet corn.More (2018) reported that the bleaching treatment of sweet corn kernels with microwaves produced a significant difference in the effect on the pH value of sweet corn [29].Bleaching treatment by placing corn kernels in the microwave for 1, 3, 5 and 7 minutes on a 540W scale resulted in a decreasing pH value.The pH value of each treatment was as follows: UB 6.81; MB1 6.75 ; MB2 6.62; MB3 6.11 and MB4 5.92.

Moisture content of sweet corn
Based on the results of the analysis of variance (Table 2) it is known that the treatment of giving a single fertilizer combination to sweet corn planted on upland did not produce a significant difference in effect (P> 0.05) on the moisture content of sweet corn.The combination of a single fertilizer is thought to have the same effect on the moisture content of sweet corn in each treatment P0 (control), P1, P2, P3 and P4.The moisture content of sweet corn for each treatment was P0 60.41%; P1 60.75%; P2 60.29%; P3 59.99% and P4 59.91%.The water content of sweet corn is relatively high, between 50-80% [30; 31].The water content of sweet corn based on cutting is classified into five types, namely: a) cutting above the germinal, b) cutting at the germinal until it breaks: c) whole seeds without rachis, d) seeds complete with flower stalks, and e) seeds complete with rachis and pedicle.The value of the water content of each sweet corn seed is a) 66.0%; b) 68.3%; c) 70.4%; d) 71.0% and e) 71.6% [32].At a glance, we can observe that the sweet corn is physically very watery with a soft texture.Research by Ansar (2021)  showed that on storage day 1 sweet corn has a moisture content value between 70-80%, storage day 5 has a moisture content value of 60-75% and storage on day 10 has a moisture content value water 50-65% [33].
The water content shows the water content possessed by the material.The higher the water content, the lower the ash content, fat content, protein content and carbohydrate content.Evangelista (2020) showed that the water content of the three varieties of sweet corn observed, namely, SC1, SC2 and SC3 showed a measurement value of 70-80% [34].The value of the water content of each variety varies greatly.However, each has a striking similarity, namely the longer the harvest time, the water content tends to decrease.This decrease in the value of the water content is accompanied by an increase in other chemical quality components such as ash content, fat content and protein content.In sweet corn that is harvested before it is physiologically ripe, it has a water content value of 83% and physiologically ripe corn is 73%.Research by Campbell, Špoljarić, Szymanek and Irawan [35][36][37][38], showed that different varieties had the same results of observing the moisture content of sweet corn.The longer the harvest time, the lower the water content value of sweet corn seeds.The water content value on the 70th day after planting was 77.10%, the 80th day after planting was 70.00% and the 90th day after planting was 56.70%.Meanwhile, the value of starch content will increase with harvesting time.The starch content value of the 70th day after planting was 54.36%, the 80th day after planting was 53.43% and the 90th day after planting was 64.09%.The longer the harvest time, the water content of sweet corn will decrease, but other chemical components will increase.This is presumably because as long as it is still not harvested the sweet corn plants continue to carry out the process of photosynthesis.During the process of photosynthesis plants need nutrients obtained from nutrients.Nutrients in the soil are absorbed and converted into carbohydrates, proteins and fats during this process.
Carbohydrates, proteins and fats that are formed will be used as food reserves by plants and accumulate in sweet corn seeds.During the generative phase, the process of filling the sweet corn kernels occurs and increasing the diameter of the sweet corn cobs.The development and increase in size due to seed filling represents the results of the growth and development stages of the corncob which generally increase in terms of size (length) and volume (diameter) [22].Seed filling represents the quality of sweet corn, while weight indicates sweet corn production so that these two parameters have a close relationship.This is shown from the results of this study that the higher the quality parameter value of sweet corn, the production is also higher.The increasing concentration of single fertilizer combinations resulted in high quality and production of sweet corn.P4 treatment is the best treatment because it has the lowest water content value so it is suspected to have other component values such as ash content, fat content, protein content and carbohydrate content which are higher than other treatments.[25; 34], stated that the formation of proteins, carbohydrates and starches takes place well in plants because nutrient needs are met.Food reserves will slowly accumulate in the seeds so that the seeds develop.During the filling, morphological and physiological changes occur until the seeds reach maturity and maximum metabolic activity.Nutrients from these fertilizers are utilized by plants in metabolic processes so that they run optimally.The results of these metabolic processes accumulate in the formation of seeds so that the seeds formed have maximum size and weight.

Ash content of sweet corn
Based on the results of the analysis of variance (Table 2) it was found that the treatment of the application of single fertilizers combination to sweet corn planted on upland did not produce a significant difference (P> 0.05) on the ash content of sweet corn.The combination of a single fertilizer is thought to have the same effect on the ash content of sweet corn in each treatment P0 (control), P1, P2, P3 and P4.The ash content of sweet corn for each treatment was P0 1.96%; P1 2.02%; P2 2.05%; P3 1.98% and P4 1.92%.
Ash content is an inorganic component of an organic material.This component generally consists of mineral substances contained.The minerals contained in 100g of sweet corn include: 7mg calcium; iron 2.71mg, magnesium 127mg, phosphorus 210mg, potassium 287mg, sodium 35mg and zinc 2.21mg.Sweet corn kernels contain the mineral zinc which accumulates in the form of Zn-phytate [39; 40].Mineral components are generally very little contained in corn kernels.Sweet corn, feed corn, glutinous corn and baby corn have a low mineral content.This low mineral content is thought to correlate with the low ash content resulting from the measurements.In this research, the measurement results showed that the ash content range of sweet corn was 1.90-2.05%.This is in line with the results of the research by Nikolic (2021) which showed that the results of measuring the ash content of the baby corn variety ZP 366 were 1.38% and those of the ZP 611k variety were 1.40% [41].Feed corn from South Maluku has been measured by a study conducted by Sinay (2021) [42].The varieties whose ash content were measured included merah delima tongkol cokelat, merah delima tongkol putih, merah darah, pulut, kuning genjah, kuning dalam and putih.The ash content values of the measurement results for each of these varieties respectively were: 1.57%, 2.04%, 1.13%, 1.69%, 1.23%, 1.39% and 1.43% [42].According to the Indonesian National Standarda/SNI (1998) regarding feed corn, the maximum ash content in corn is 2% [43].The results showed that the ash content of sweet corn was still within the range required by SNI.
Several studies, including by Irawan (2019), show that the longer the harvesting age, the higher the ash content in sweet corn [38].The value of ash content on the 70th day after planting was 2.33%, the 80th day after planting was 2.99% and the 90th day after planting was 3.00%.This is in line with the research of Evangelista (2020) which results in an average ash content value that tends to increase with the length of harvesting [34].Each variety showed a value of ash content which tended to increase due to harvesting time.The value of the ash content of variety SC1 after physiological ripening on day 18 was 3.40% and day 20 was 4.00%.SC2 variety after physiological ripening on day 18 was 3.98% and day 20 was 4.08%.SC3 variety after physiological ripening on day 18 was 3.08% and day 20 was 3.71%.The relatively high ash content value in sweet corn is thought to be due to the different soil conditions and fertilizers used for planting.Land conditions with optimal irrigation can help plants absorb nutrients available in the soil.Nutrients from fertilization will be used by plants to produce food reserves.The food reserves of sweet corn are accumulated in the seeds.Ash content is the inorganic or mineral content contained in food [44].Nikolic (2021) stated that a high ash content value indicates a high mineral content in the food [41].According to Sinay (2021) corn kernels contain various minerals including: macro minerals such as potassium, calcium and magnesium as well as micro minerals or trace elements such as zinc, manganese, boron and others [42].

Fat content of sweet corn
Based on the results of the analysis of variance (Table 2) it was found that the treatment of the application of single fertilizers combination to sweet corn grown on upland did not produce a significant difference in effect (P> 0.05) on the fat content of sweet corn.The combination of a single fertilizer is thought to have the same effect on the fat content of sweet corn in each treatment P0 (control), P1, P2, P3 and P4.The fat content of sweet corn for each treatment was P0 0.62%; P1 0.53%; P2 0.43%; P3 0.52% and P4 0.40%.
Fat content is the oil extracted from the extraction of food ingredients.The fat content depends on the type of food observed.In foods that have the ability to store food reserves in the form of oil, the fat produced in the measurement will be high.However, for plants such as corn, in general, the fat generated from measuring the fat content will be relatively low because corn stores food reserves in the form of starch.100 g of sweet corn contains 0.667 g of saturated fat, 1.251 g of single bond unsaturated fat and 2.163 g of double bond unsaturated fat [39].Budak (2018) reported that various varieties of sweet corn contain varying amounts of fat [45].The vega variety contains a fat content of 4.4%; merit 4.1%; jubilee 4.2%; lincoln 4.4% and sakarya 4.6%.According to Evangelista (2021) the average fat content value tends to increase with the length of harvest [34].Each variety shows a value of fat content that tends to increase due to harvesting time.The value of the fat content of the SC1 variety after physiological ripening on the 18th day was 5.13% and 3.89% on the 20th day.SC2 variety after physiological ripening on day 18 was 3.20% and day 20 was 5.78%.SC3 variety after physiological ripening on day 18 was 3.42% and day 20 was 4.15%.The high fat content value in these sweet corn varieties is thought to be due to better soil conditions and fertilizers used for planting than the land in this study.Land conditions with adequate irrigation can help plants to absorb nutrients available in the soil.Nutrients from 1230 (2023) 012052 IOP Publishing doi:10.1088/1755-1315/1230/1/01205210 fertilization will be used by plants to produce food reserves.The food reserves of sweet corn are accumulated in the seeds.
According to Aniya (2019), during the growth stage, plants need nutrients which are provided through fertilization [26].Plant metabolism runs optimally during the photosynthesis process because the need for sufficient nutrients, sunlight and water are met.The optimal cell metabolism produces various substances such as carbohydrates, proteins and fats.The resulting photosynthate will be transferred and stored in the seeds during seed filling.In this study the average value of the resulting fat content was lower when compared to other studies.This is presumably because the land used is land with inadequate irrigation.The results of soil testing with a portable test kit showed that the soil on the land contains a pH of 5-6 (slightly acidic), low organic C, medium P and low K.These soil conditions cause the soil to become less fertile.In addition to nutrients and poor soil conditions, irrigation of the soil is also quite difficult because it solely depends on rain.Upland is land management by implementing the use of water to fully utilize rainwater in the cultivation of plants and there is no standing water in the long term.Soil fertility on upland is generally relatively low, especially on land that is experiencing erosion.Acidic soil is also an indicator of the physical properties of the soil and needs attention.This physical property can be seen from the low pH level, which is <5.50.In addition, high Al content, high P fixation, low category of cation exchange capacity, Fe and Mn content which almost reached the threshold.Fe and Mn content exceeding these limits can poison plants.Soil types with these characteristics are mostly inceptisols, ultisols, and oxisols, and are spread across the islands of Kalimantan, Sumatra, and Papua [46; 47].
The fat content of sweet corn for each treatment was P0 0.62%; P1 0.53%; P2 0.43%; P3 0.52% and P4 0.40%.The average fat content is still below the maximum fat content for corn for feed raw material [43].The average fat content is much lower than the results of the study by Sinay (2021) who reported that seven local South Maluku maize varieties had varying levels of fat [42].The varieties included merah delima tongkol cokelat, merah delima tongkol putih, merah darah, pulut, kuning genjah, kuning dalam and putih.The fat content values from the measurement results of each of these varieties were: 4.94%, 4.24%, 3.47%, 4.70%, 5.10%, 3.90% and 3.57%.The value of low-fat content has its own advantages.Fat is a compound that is easily oxidized so it is easily damaged and is characterized by a rancid odor.During storage, the fat content undergoes oxidation reactions.Fat oxidation causes a rancid odor in stored products.It was reported that sweet corn rarely produces rancid odors, because the fat content of sweet corn is only a little, which is around 2.60% [48].

Conclusion
The conclusion of the study is that the best treatment is found in P4.The combination of a single urea fertilizer: SP36: KCl on sweet corn grown on upland with a concentration of 25.76g/plant produced the highest values for weight, cob length and cob diameter, fairly neutral pH, lowest water content, low ash content and lowest fat content.The values of each parameter include: weight 199.13g; cob length 141.02%; cob diameter 37.55%, pH 5.38; water content 59.91%; ash content 1.92% and fat content 0.40%.The value of the ash content and fat content parameters are still in accordance with the SNI 01-4483-1998 standard regarding corn for feed raw material.

Table 1 .
Average weight, cob length and cob diameter of sweet corn.

Table 2 .
Average pH, moisture content, ash content and fat content of sweet corn.